Hi, twobits. Are you running a linux distro already on this hardrive that uses grub as its bootloader. Because you can get a kernel panic because pclos 2009 I think uses lilo. There is a cheat code you can also try at the live cd boot screen
You haven't posted your computer specs yet to show how much ram you are running on this pc. I never got pclos (minnie me or the full distro) to boot up on any of my computers either. So I moved on to other distros like Ubuntu,Mint,Mepis,Debian. Some Hardware won't run with certain Linux distros because of the way the kernel is configured for that certain distro.
Look through
PCLinuxOS-Forums - Index and post your query there as those members run that particular distro.
Kernel Panic can also be caused by burning the cd at too fast a speed when burning. Try burning it at 4x speed. Also do a md5sum check of downloaded iso file with
WINMD5SUM to validate integrity of download.
I don't think that memory timing is a issue here(though you say you have had this issue before and changeing ram timing fixed this). Could be all the reasons I listed above or Video Card/Chip related. you may also refer to this thread
PCLinuxOS
My last recommendation is to make sure no USB devices are plugged into your computer when you try to boot the live cd. I don't know if you are running live, or have installed already. Kernel panic is usually a boot message so that is why I tried to cover everything.