<Solved> Curious GRUB Behavior

[SpinheadMickey]

   3 wks ago I added a second HDD to a friend's 2007 HP desktop (don't have sys specs on hand, but can get if needed). Installation went flawlessly, XP boots fine, etc. When GRUB bootscreen appears, if you let the countdown timer run down the system boots fine. If, however, you press 'Enter' to boot the selected entry (PCLOS is default), boot fails with kernel panic. So long as you let the timer run down and boot default selection, it boots just fine. Any idea what might cause this?
 
 I must note that the friend is fine with it, so long as PCLinux boots. This is not causing any usability issues for him, I'm just curious about why GRUB would exhibit this behavior.

[Old-Polack]

   3 wks ago I added a second HDD to a friend's 2007 HP desktop (don't have sys specs on hand, but can get if needed). Installation went flawlessly, XP boots fine, etc. When GRUB bootscreen appears, if you let the countdown timer run down the system boots fine. If, however, you press 'Enter' to boot the selected entry (PCLOS is default), boot fails with kernel panic. So long as you let the timer run down and boot default selection, it boots just fine. Any idea what might cause this?
 
 I must note that the friend is fine with it, so long as PCLinux boots. This is not causing any usability issues for him, I'm just curious about why GRUB would exhibit this behavior.

Having three hard drives in this machine, and having had as many as seven hard drives in previous machines, with up to 20+ Linux installations, you have to get to know grub, if you don't want to go insane.        ...oops, too late... 

To know what is actually happening on that machine we'd need to see the contents of its /boot/grub/menu.lst, and the output from the command, as root;

[root@localhost ~]# fdisk -l                    <Enter>  <-- That's a lower case letter L not a number 1

At least, that would give us a working starting point to finding a solution.

[SpinheadMickey]

Sorry, Old-Polack, for the long wait on the reply (I am currently without internet thanks to our local provider selling our service area to a provider that is not currently providing!). Anyway, i think I found the problem. It turns out that the kernel panic was occurring at random times in the boot process. Sometimes it would make to the KDE splash screen, but would panic just before bringing up the desktop. But always it would only boot if the timer expired at the GRUB boot screen. This PC has an ATI Radeon 200M video card onboard. I changed the driver from proprietary to xorg and now it boots just fine every time. Kinda confused as to why that would cause boot problems if you press 'Enter' at the boot screen, but for whatever reason it is working now.