Using a SuSE 9.1 system, I'm logged in as rich, who belongs to the group users. Though I've tried to set group for a directory to users and the access for that group to rw, members of that group (e.g. rich) are unable to access the directory ('permission denied' message). Some current info from the console showing the fstab file and 'windows' directory that is a target:

**************************************************************************************************** *******

rich@beer:~> cat /etc/fstab

/dev/hda1 / reiserfs acl,user_xattr 1 1
/dev/hda3 /windows/C vfat users,gid=users,umask=0002,iocharset=utf8 0 0
/dev/hda5 /windows/E vfat users,gid=users,umask=0002,iocharset=utf8,suid 0 0
/dev/hda2 swap swap pri=42 0 0
devpts /dev/pts devpts mode=0620,gid=5 0 0
proc /proc proc defaults 0 0
usbfs /proc/bus/usb usbfs noauto 0 0
sysfs /sys sysfs noauto 0 0
/dev/dvd /media/dvd subfs fs=cdfss,ro,procuid,nosuid,nodev,exec,iocharset=utf8 0 0
/dev/dvdrecorder /media/dvdrecorder subfs fs=cdfss,ro,procuid,nosuid,nodev,exec,iocharset=utf8 0 0
/dev/fd0 /media/floppy subfs fs=floppyfss,procuid,nodev,nosuid,sync 0 0
/dev/hdc5 /xtra reiserfs defaults 1 2
/dev/hdc1 /windows/D vfat umask=000 0 0

rich@beer:~> ls -l /

total 200
drwxr-xr-x 2 root root 2864 2005-05-20 16:02 bin
drwxr-xr-x 3 root root 520 2005-05-10 11:03 boot
drwxr-xr-x 34 root root 180568 2006-09-14 12:29 dev
drwxr-xr-x 61 root root 6392 2006-09-14 12:53 etc
drwxr-xr-x 4 root root 104 2006-09-13 17:08 home
drwxr-xr-x 12 root root 3096 2005-05-20 16:01 lib
drwxr-xr-x 5 root root 128 2004-04-06 09:04 media
drwxr-xr-x 2 root root 48 2004-04-06 09:04 mnt
drwxr-xr-x 8 root root 224 2006-03-16 10:33 opt
dr-xr-xr-x 91 root root 0 2006-09-14 05:28 proc
drwx------ 35 root root 1728 2006-09-14 13:33 root
drwxr-xr-x 3 root root 7752 2005-05-20 16:02 sbin
drwxr-xr-x 4 root root 96 2005-05-10 10:51 srv
drwxr-xr-x 8 root root 0 2006-09-14 05:28 sys
drwxrwxrwt 61 root root 2664 2006-09-14 14:15 tmp
drwxr-xr-x 12 root root 344 2005-05-10 10:58 usr
drwxr-xr-x 14 root root 360 2005-05-10 10:53 var
drw-rw---- 5 root users 192 2006-03-31 10:01 windows
drwxrwxrwx 21 rich users 552 2006-06-26 02:35 xtra

rich@beer:~> groups rich

rich : users uucp dialout audio video

rich@beer:~> id

uid=1000(rich) gid=100(users) groups=14(uucp),16(dialout),17(audio),33(video),100(users)

rich@beer:~> cd /windows

bash: cd: /windows: Permission denied

**************************************************************************************************** *****

Where have I errored?

rich

All directories have to have the executable bit set.
(Just the way it is)

drw-rw---- 5 root users 192 2006-03-31 10:01 windows

chmod 770 /windows should work

or mebbe 771...

You can change permissions once inside the directory to remove the x.

Yes, you should set also X (executable for files, accessible for directories), check that in man chmod