It happened last night. First, I install a software which might not be compatible with Snow Leopard. Then, when I launched the app for the first time, my laptop froze and couldn't even execute force quit command. I did a restart. After seeing the apple logo, the start-up ended in a blank gray screen. The list below shows the things I've tried: 1. Snow Leopard disc boot: same gray screen. 2. Launching another SL via firewire: either gay screen or blue screen. 3. Safe mode: worked at the first few times, and I tried to reboot immediately but seeing the same gray screen again. I backed up important files in safe mode and did repair permissions(fixed a lot of problems that are related to safari) and verify HD (no problem found), but it didn't help. 4. Single user mode: launched and ran /sbin/fsck -fy few times till it said "The volume (name_of_volume) appears to be OK." However, this didn't help either. 5. This might has been a stupid thing that I've tried after the safe mode didn't even work anymore I took the HD out and formatted using a windows PC (i don't have another mac) and hope I can a fresh install. However, when starting up, all I can see now are first the gray screen (without apple logo) and then the black screen. I took it to the genius bar, and they couldn't figured out why and want me to pay $310 flat rate to fix it. I just want to see if there's anything else I could try before spending $310. The laptop is a 17" core2due 2.33G model. I really appreciate any help, and thank you guys in advance. Sorry about any misspellings and grammatical errors.