My friend sent me his Hp pavilion ZT1000 for me to fix...
1. laptop randomly crashes whenever it feels like it (1 sec- 3 hrs)
2. While it's crashed, the lcd still displays the last image, but no form of imput works.
3. Sometimes, it boots up to a blank screen, but everything works (can hear fan, hd, and even cd rom spin up, but blank screen)
4. When plugged into annother monitor, it behaves the same way as the lcd screen.
Have you tried a memory tester like MemTest86? It's on the newer Knoppix discs, or it can be downloaded either as a floppy-disk image or as an ISO bootable CD-ROM image.