I have a debian server (wheezy) which is running an apache2 server and a squid proxy.
Today I tried to view squid log files (as root) and got "permission denied" on trying to enter the /var/log/squid directory.
I then tried sylog and got the same result.
Trying to enter the /root directory or any other directory owned by root with drwx------ permissions gives the same result too.
All was OK on Friday when I last viewed the squid logs.
Any suggestions as to what the problem may be?

Thanks,
James

the usual reason is you tried it as non-root user.
Otherwise please show us exactly what have you tried and explain what have you modified since Friday.

As stated I'm attempting this as root. I have changed nothing (or even logged in) since Friday.

Can you post the output of this command (run as root):
jdk

login as: j1
j1@192.168.10.93's password:

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
You have mail.
Last login: Mon Oct 12 09:43:57 2015 from j1office.xxxxxxxxxxxxxx.xxx
j1@squid2:~$ su
Password:
root@squid2:/var/www/wordpress$ cd /root
bash: cd: /root: Permission denied
root@squid2:/var/www/wordpress$ cat /var/log/syslog
cat: /var/log/syslog: Permission denied
root@squid2:/var/www/wordpress$ cd /var/log
root@squid2:/var/log$ ls -l
total 1188
-rw-r--r-- 1 root root 0 Jul 24 06:25 alternatives.log
-rw-r--r-- 1 root root 2709 Jul 23 13:34 alternatives.log.1
-rw-r--r-- 1 root root 231 Oct 16 2014 alternatives.log.2.gz
-rw-r--r-- 1 root root 2149 Oct 16 2013 alternatives.log.3.gz
drwxr-x--- 8 root adm 4096 Oct 11 06:25 apache2
drwxr-xr-x 2 root root 4096 Jul 24 06:25 apt
-rw-r--r-- 1 root root 0 Nov 1 2013 aptitude
-rw-r--r-- 1 root root 209 Oct 14 2013 aptitude.1.gz
-rw-r----- 1 root adm 25252 Oct 12 11:37 auth.log
-rw-r----- 1 root adm 131427 Oct 11 06:25 auth.log.1
-rw-r----- 1 root adm 8638 Oct 4 06:25 auth.log.2.gz
-rw-r----- 1 root adm 8740 Sep 27 06:25 auth.log.3.gz
-rw-r----- 1 root adm 8759 Sep 20 06:25 auth.log.4.gz
-rw-rw---- 1 root utmp 0 Oct 1 06:25 btmp
-rw-rw---- 1 root utmp 0 Sep 1 06:25 btmp.1
drwxr-xr-x 2 clamav clamav 4096 Oct 11 06:25 clamav
-rw-r----- 1 root adm 5012 Oct 12 09:25 daemon.log
-rw-r----- 1 root adm 5103 Sep 2 07:07 daemon.log.1
-rw-r----- 1 root adm 1432 Aug 25 07:24 daemon.log.2.gz
-rw-r----- 1 root adm 1469 Aug 10 10:10 daemon.log.3.gz
-rw-r----- 1 root adm 2569 Jul 23 13:42 daemon.log.4.gz
drwxr-xr-x 2 dansguardian dansguardian 4096 Oct 12 06:25 dansguardian
drwxr-xr-x 2 root root 4096 Oct 15 2013 dbconfig-common
-rw-r----- 1 root adm 28154 Oct 12 09:25 debug
-rw-r----- 1 root adm 167 Oct 5 14:48 debug.1
-rw-r----- 1 root adm 151 Sep 26 18:24 debug.2.gz
-rw-r----- 1 root adm 143 Sep 23 11:08 debug.3.gz
-rw-r----- 1 root adm 4268 Sep 2 07:07 debug.4.gz
-rw-r----- 1 root adm 51699 Oct 12 09:25 dmesg
-rw-r----- 1 root adm 51841 Sep 2 07:07 dmesg.0
-rw-r----- 1 root adm 12789 Aug 25 07:23 dmesg.1.gz
-rw-r----- 1 root adm 12937 Aug 10 10:10 dmesg.2.gz
-rw-r----- 1 root adm 12728 Jul 23 13:41 dmesg.3.gz
-rw-r----- 1 root adm 13805 Jul 23 09:30 dmesg.4.gz
-rw-r--r-- 1 root root 0 Jul 24 06:25 dpkg.log
-rw-r--r-- 1 root root 39091 Jul 23 13:35 dpkg.log.1
-rw-r--r-- 1 root root 212 Nov 5 2014 dpkg.log.2.gz
-rw-r--r-- 1 root root 921 Oct 16 2014 dpkg.log.3.gz
-rw-r--r-- 1 root root 214 Oct 15 2014 dpkg.log.4.gz
-rw-r--r-- 1 root root 1303 Nov 27 2013 dpkg.log.5.gz
-rw-r--r-- 1 root root 21039 Oct 16 2013 dpkg.log.6.gz
drwxr-s--- 2 Debian-exim adm 4096 Nov 28 2013 exim4
-rw-r--r-- 1 root root 323904 Nov 27 2013 faillog
drwxr-xr-x 2 root root 4096 Oct 14 2013 fsck
drwxr-xr-x 3 root root 4096 Oct 14 2013 installer
-rw-r----- 1 root adm 77612 Oct 12 09:25 kern.log
-rw-r----- 1 root adm 126 Oct 7 14:39 kern.log.1
-rw-r----- 1 root adm 149 Oct 5 14:48 kern.log.2.gz
-rw-r----- 1 root adm 151 Sep 26 18:24 kern.log.3.gz
-rw-r----- 1 root adm 143 Sep 23 11:08 kern.log.4.gz
-rw-rw-r-- 1 root utmp 2955624 Oct 12 11:37 lastlog
-rw-r----- 1 root adm 0 Oct 14 2013 lpr.log
-rw-r----- 1 root adm 0 Oct 14 2013 mail.err
-rw-r----- 1 root adm 2186 Oct 12 11:12 mail.info
-rw-r----- 1 root adm 14801 Oct 9 19:05 mail.info.1
-rw-r----- 1 root adm 3591 Oct 3 22:40 mail.info.2.gz
-rw-r----- 1 root adm 3151 Sep 25 22:38 mail.info.3.gz
-rw-r----- 1 root adm 2745 Sep 19 21:22 mail.info.4.gz
-rw-r----- 1 root adm 2186 Oct 12 11:12 mail.log
-rw-r----- 1 root adm 14801 Oct 9 19:05 mail.log.1
-rw-r----- 1 root adm 3591 Oct 3 22:40 mail.log.2.gz
-rw-r----- 1 root adm 3151 Sep 25 22:38 mail.log.3.gz
-rw-r----- 1 root adm 2745 Sep 19 21:22 mail.log.4.gz
-rw-r----- 1 root adm 0 Oct 14 2013 mail.warn
-rw-r----- 1 root adm 50202 Oct 12 09:25 messages
-rw-r----- 1 root adm 2699 Oct 11 06:25 messages.1
-rw-r----- 1 root adm 335 Oct 4 06:25 messages.2.gz
-rw-r----- 1 root adm 424 Sep 27 06:25 messages.3.gz
-rw-r----- 1 root adm 407 Sep 20 06:25 messages.4.gz
drwxr-s--- 2 mysql adm 4096 Oct 15 2013 mysql
-rw-r----- 1 mysql adm 0 Oct 15 2013 mysql.err
-rw-r----- 1 mysql adm 0 Oct 12 06:25 mysql.log
-rw-r----- 1 mysql adm 20 Oct 11 06:25 mysql.log.1.gz
-rw-r----- 1 mysql adm 20 Oct 10 06:25 mysql.log.2.gz
-rw-r----- 1 mysql adm 20 Oct 9 06:25 mysql.log.3.gz
-rw-r----- 1 mysql adm 20 Oct 8 06:25 mysql.log.4.gz
-rw-r----- 1 mysql adm 20 Oct 7 06:25 mysql.log.5.gz
-rw-r----- 1 mysql adm 20 Oct 6 06:25 mysql.log.6.gz
-rw-r----- 1 mysql adm 20 Oct 5 06:25 mysql.log.7.gz
drwxr-xr-x 2 root root 4096 Oct 14 2013 news
drwxr-xr-x 2 ntp ntp 4096 May 12 2012 ntpstats
-rw-r--r-- 1 root root 21374 Oct 9 06:25 popularity-contest
-rw-r--r-- 1 root root 21036 Oct 2 06:25 popularity-contest.0
-rw-r--r-- 1 root root 6202 Sep 25 06:25 popularity-contest.1.gz
-rw-r--r-- 1 root root 6194 Sep 18 06:25 popularity-contest.2.gz
-rw-r--r-- 1 root root 6174 Sep 11 06:25 popularity-contest.3.gz
-rw-r--r-- 1 root root 6178 Sep 4 06:25 popularity-contest.4.gz
-rw-r--r-- 1 root root 6222 Aug 28 06:25 popularity-contest.5.gz
-rw-r--r-- 1 root root 6202 Aug 21 06:25 popularity-contest.6.gz
drwxr-x--- 3 root adm 20480 Oct 11 06:25 samba
drwxr-x--- 2 proxy proxy 4096 Oct 12 06:25 squid
-rw-r----- 1 root adm 88566 Oct 12 11:17 syslog
-rw-r----- 1 root adm 17441 Oct 12 06:25 syslog.1
-rw-r----- 1 root adm 1096 Oct 11 06:25 syslog.2.gz
-rw-r----- 1 root adm 1787 Oct 10 06:25 syslog.3.gz
-rw-r----- 1 root adm 1957 Oct 9 06:25 syslog.4.gz
-rw-r----- 1 root adm 2053 Oct 8 06:25 syslog.5.gz
-rw-r----- 1 root adm 1975 Oct 7 06:25 syslog.6.gz
-rw-r----- 1 root adm 1823 Oct 6 06:25 syslog.7.gz
-rw-r----- 1 root adm 615 Oct 12 09:25 user.log
-rw-r----- 1 root adm 2708 Oct 10 06:25 user.log.1
-rw-r----- 1 root adm 216 Oct 3 06:25 user.log.2.gz
-rw-r----- 1 root adm 369 Sep 26 06:25 user.log.3.gz
-rw-r----- 1 root adm 203 Sep 19 06:25 user.log.4.gz
-rw-r----- 1 root adm 132 Oct 12 04:48 vsftpd.log
-rw-r----- 1 root adm 1435 Oct 10 18:00 vsftpd.log.1
-rw-r----- 1 root adm 67 Sep 28 14:29 vsftpd.log.2
-rw-r----- 1 root adm 618 Sep 27 00:19 vsftpd.log.3
-rw-r----- 1 root adm 197 Sep 18 05:16 vsftpd.log.4
-rw-rw-r-- 1 root utmp 8064 Oct 12 11:37 wtmp
-rw-rw-r-- 1 root utmp 4608 Sep 15 14:23 wtmp.1
root@squid2:/var/log$ cd squid
bash: cd: squid: Permission denied
root@squid2:/var/log$ cd samba
bash: cd: samba: Permission denied
root@squid2:/var/log$

root@squid2:/var/log$ ls -l /var/log/squid
ls: cannot open directory /var/log/squid: Permission denied
root@squid2:/var/log$

This is odd. A few things I would try:
How do you become root - by logging in as root, or by running "su"? Do both methods work?
Apart from entering directories, are there other root-only activities you can't do, such as useradd?
Have you run "id" to check if you are really root and have UID 0?
What if you create a directory as root, can you cd into it? And after chmod 700?
What if you boot into single-user mode?

That's interesting..........

root@squid2:/var/log$ id
uid=1079(root) gid=65534(nogroup) groups=65534(nogroup)
root@squid2:/var/log$

yes, try id to check "yourself" and probably go into /tmp, create some files and check permissions on that. Is selinux enabled?

grep :0: /etc/passwd

Next test: more /etc/passwd.

Not familiar with selinux so probably not.

---------- Post added 10-12-15 at 11:52 AM ----------

root@squid2:/var/log$ more /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:x:13:13roxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www/wordpress:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
irc:x:39:39:ircd:/var/run/ircd:/bin/sh
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
libuuid:x:100:101::/var/lib/libuuid:/bin/sh
Debian-exim:x:101:103::/var/spool/exim4:/bin/false
statd:x:102:65534::/var/lib/nfs:/bin/false
sshd:x:103:65534::/var/run/sshd:/usr/sbin/nologin
j1:x:1000:1000:j1,,,:/var/www/wordpress:/bin/bash
clamav:x:104:106::/var/lib/clamav:/bin/false
dansguardian:x:105:107ansGuardian User,,,:/var/log/dansguardian:/bin/sh
mysql:x:106:108:MySQL Server,,,:/nonexistent:/bin/false
ntp:x:107:110::/home/ntp:/bin/false
messagebus:x:108:112::/var/run/dbus:/bin/false
avahi:x:109:113:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/bin/false
ftp:x:110:115:ftp daemon,,,:/srv/ftp:/bin/false
web:x:10121:33::/home/web:/bin/sh
postfix:x:111:116::/var/spool/postfix:/bin/false
root@squid2:/var/log$

root@squid2:/var/log$ grep :0: /etc/passwd
root:x:0:0:root:/root:/bin/bash

So, su is playing tricks. Try type su. Try sudo, and if /etc/sudoers is not set up, boot into single user mode and set it up. Reinstall su.

It does the same if I log in directly as root

login as: root
root@192.168.10.93's password:

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Mon Oct 12 09:26:53 2015 from j1office.callington-comm.cornwall.sch.uk
Could not chdir to home directory /home/CSE/root: No such file or directory
root@squid2:/$ id
uid=1079(root) gid=65534(nogroup) groups=65534(nogroup)
root@squid2:/$