About 6 months ago, I started running into problems with new HP laptops. The issue usually manifests itself as extremely slow SATA harddrive performance. Intel's ICH8+ chipsets allow for a AHCI/IDE combination mode which confuses the heck out of the kernel.
This can be selected in the BIOS. Locking in AHCI would be the preferred way, but it completely locks out real IDE devices if they are present because the kernel will not go looking for them (in HP's case: the CD drives...)
The other option is to set the BIOS to something other than AHCI, and add the ide0=noprobe boot parameter.
Is there any way you can compare the boot parameters between GRUB and LILO?
(Warning: if this is a dual boot setup with Windows, do not change the BIOS option. Windows will no longer boot.)