Hi,
I installed PCLinuxOS yesterday on my laptop. It has a windows partition, a centos partition and now a pc linux os partition.
I installed grub when I installed pclinux, however now it does not boot into any of the linux partitions. The grub menu appears, I select Windows and that works fine. However when I select any two of the linux systems, it doesn't boot and comes up with a kernal panic error on both. The error goes along these lines, kernel panic, not syncing. Does anyone know what's happened, the centos partition was working fine, its only when I installed pclinux that it messed that one up too. Thanks in advance.

When you installed PCLinuxOS, did you install Grub to the master boot record?
It would be helpful if you could post some drive/partition and boot file info. You could boot your PCLinux Live CD and go to the site below, read the instructions, download the bootinfoscript, run it and post the output - results.txt file here:

http://sourceforge.net/projects/bootinfoscript/

rescue centos with cd/dvd

after chroot

install grub2

Yes. I installed grub to the MBR. ok ill do that now and get back to you.

How will chroot help in this incident?

Here is the output of that script:

[root@livecd centoslive]# ./bootinfoscript bootinfo.txt

Boot Info Script 0.61 [1 April 2012]

Identifying MBRs...
Computing Partition Table of /dev/sda...
Computing Partition Table of /dev/sdb...
Searching sda1 for information...
Searching sda2 for information...
Searching sda3 for information...
Searching sda5 for information...
Searching sdb1 for information...

Finished. The results are in the file "bootinfo.txt"
located in "/home/centoslive/".

[root@livecd centoslive]# ls
bootinfoscript Desktop Downloads Pictures Templates
bootinfo.txt Documents Music Public Videos
[root@livecd centoslive]# cat bootinfo.txt
Boot Info Script 0.61 [1 April 2012]


============================= Boot Info Summary: ===============================

=> Grub Legacy (v0.97) is installed in the MBR of /dev/sda and looks on the
same drive in partition #7 for /boot/grub/stage2 and /boot/grub/menu.lst.
=> Syslinux MBR (4.04 and higher) is installed in the MBR of /dev/sdb.

sda1: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows Vista/7: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Mounting failed: mount: unknown filesystem type 'ntfs'
./bootinfoscript: line 2376: ntfs-3g: command not found

sda2: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows Vista/7: NTFS
Boot sector info: According to the info in the boot sector, sda2 has
99324208 sectors, but according to the info from
fdisk, it has 104148991 sectors.
Mounting failed: mount: unknown filesystem type 'ntfs'
./bootinfoscript: line 2376: ntfs-3g: command not found
mount: unknown filesystem type 'ntfs'
./bootinfoscript: line 2376: ntfs-3g: command not found

sda3: __________________________________________________________________________

File system: Extended Partition
Boot sector type: -
Boot sector info:

sda5: __________________________________________________________________________

File system: swap
Boot sector type: -
Boot sector info:

sdb1: __________________________________________________________________________

File system: vfat
Boot sector type: SYSLINUX 4.06 4.06-pre1
Boot sector info: Syslinux looks at sector 7878 of /dev/sdb1 for its
second stage. SYSLINUX is installed in the directory.
No errors found in the Boot Parameter Block.
Operating System:
Boot files: /syslinux/syslinux.cfg /efi/boot/boot.efi
/efi/boot/bootia32.efi /ldlinux.sys

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 206,847 204,800 7 NTFS / exFAT / HPFS
/dev/sda2 206,848 104,355,839 104,148,992 7 NTFS / exFAT / HPFS
/dev/sda3 104,361,984 488,359,935 383,997,952 f W95 Extended (LBA)
/dev/sda5 482,215,936 488,359,935 6,144,000 82 Linux swap / Solaris
Invalid MBR Signature found.
EBR refers to a location outside the hard drive.


Drive: sdb _____________________________________________________________________

Disk /dev/sdb: 1031 MB, 1031798784 bytes
16 heads, 32 sectors/track, 3936 cylinders, total 2015232 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sdb1 * 32 2,015,231 2,015,200 c W95 FAT32 (LBA)


"blkid" output: ________________________________________________________________

Device UUID TYPE LABEL

/dev/loop0 squashfs
/dev/loop2 squashfs
/dev/loop3 b67839c9-6c46-48fc-b629-32737f115c50 ext4 _CentOS-6.2-i386
/dev/loop4 DM_snapshot_cow
/dev/mapper/live-osimg-min b67839c9-6c46-48fc-b629-32737f115c50 ext4 _CentOS-6.2-i386
/dev/mapper/live-rw b67839c9-6c46-48fc-b629-32737f115c50 ext4 _CentOS-6.2-i386
/dev/sda1 889C0B149C0AFD06 ntfs System Reserved
/dev/sda2 4ECC18F1CC18D555 ntfs
/dev/sda5 bc5cb967-f623-4812-b9dc-e5774b8c7c43 swap
/dev/sdb1 12FD-1C66 vfat PENDRIVE

========================= "ls -R /dev/mapper/" output: =========================

/dev/mapper:
control
live-osimg-min
live-rw

================================ Mount points: =================================

Device Mount_Point Type Options

/dev/mapper/live-rw / ext4 (rw,noatime)
/dev/sdb1 /mnt/live vfat (rw)


========================= sdb1/syslinux/syslinux.cfg: ==========================

--------------------------------------------------------------------------------

default vesamenu.c32
timeout 100

menu background splash.jpg
menu title Welcome to your CentOS LiveUSB
menu color border 0 #ffffffff #00000000
menu color sel 7 #ffffffff #ff000000
menu color title 0 #ffffffff #00000000
menu color tabmsg 0 #ffffffff #00000000
menu color unsel 0 #ffffffff #00000000
menu color hotsel 0 #ff000000 #ffffffff
menu color hotkey 7 #ffffffff #ff000000
menu color timeout_msg 0 #ffffffff #00000000
menu color timeout 0 #ffffffff #00000000
menu color cmdline 0 #ffffffff #00000000
menu hidden
menu hiddenrow 5
label linux0
menu label Boot
kernel vmlinuz0
append initrd=initrd0.img root=LABEL=PENDRIVE rootfstype=vfat rw quiet liveimg
menu default
label linuxtext0
menu label Boot (text mode)
kernel vmlinuz0
append initrd=initrd0.img root=LABEL=PENDRIVE rootfstype=vfat rw quiet liveimg 3
label installer
menu label Network Installation
kernel vminst
append initrd=install.img text
label memtest
menu label Memory Test
kernel memtest
label local
menu label Boot from local drive
localboot 0xffff
--------------------------------------------------------------------------------

================= sdb1: Location of files loaded by Syslinux: ==================

GiB - GB File Fragment(s)

?? = ?? ldlinux.sys 1
?? = ?? syslinux/syslinux.cfg 1
?? = ?? syslinux/vesamenu.c32 1

============== sdb1: Version of COM32(R) files used by Syslinux: ===============

syslinux/vesamenu.c32 : COM32R module (v4.xx)

=============================== StdErr Messages: ===============================

No volume groups found
mdadm: No arrays found in config file or automatically

Also fdisk -l displayed this output:
[root@livecd centoslive]# fdisk -l

Unable to seek on /dev/sda

Your output doesn't show the information generally provided by the bootinfoscript, or at least only about a third of what one would expect. I don't know what went wrong. You can see that Grub Legacy is in the mbr of sda and looks for boot files on sda7 and sda7 does not show in the output. fdisk was not able to read sda so do you have GParted on the CentOS flash? If so, post the output to see if sda7 is recognized. Yo might try running the bootinfoscript again as the output was incomplete for some reason.

I decided to giveup and just install it all again. Lost some files. Hate linux sometimes...

That was about rescuing from CentOS cd/dvd

It will guide you.
mount your install at /mnt/sysimage (select this)

chroot /mnt/sysimage
grub2-mkconfig
grub2-install /dev/sda