try this,
1.Set your bios boot order back to the original setup.
2. boot maverick edit you /etc/grub.d/40_custom file with the following then rerun update grub;
3.Boot the usb key back into the slackware installer and run setup. Select your slackware swap and root partitions when asked, but do not format.
Skip the software installtion section and go to the configuration section and rerun it. at the lilo section, select simple method and the root partition when asked where to install lilo. you can cancel/skip the rest of the configuration. reboot and see what happens.

Hey man, I appreciate all your help. Apparently, my issue seems to be hardware related because I have SATA & PATA drives in different slots which cause the device names to swap.

Another users said he's seen this problem before. So it would be pointless trying to solve the slackware boot issue if drives keep swapping on me. Basically I need to ditch my PATA drive which has bad blocks anyway and just get a new SATA drive.

Kinda feel bad we couldn't get anywhere because you've been so helpful.

At least you was able to figure out what the problem was.

True, true. Thanks again man. I'll see you around the forums.