NEED HELP! (Macbook Pro Gray screen)

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.

madog said:

Are you able to boot up while holding down the OPTION key with a system disk inserted?

If you can boot up to it and launch Disk Utility, you should be able to format the drive if nothing else is wrong with it.

Click to expand...

you mean the cd? I've tried that. the cd shows up, but it gives me the same gray screen when boot form it.

michaelfengdayu said:

Insert the disk that comes with your computer. Boot up while holding down "D". And see the result.

Click to expand...

thank you so much for helping.
I did that and something interesting happened: I see a blue screen instead when booting from the CD, and I can boot into the system on a external HD via firewire. What should I do now?

btw, I thought power+command+ctrl can restart the macbook Pro, but it didn't work; it just shuts down.

michaelfengdayu said:

You can go to Disk Utility and reformat your HDD in your computer. But I would do a Hardware Test.

Click to expand...

I reformatted the HD successfully, but the problem still exist. Booting from both the snow leopard disk and external HD shows the blue screen now.

michaelfengdayu said:

Any error messages in the Hardware Test?

Click to expand...

I didn't run the test because I thought it only can be performed via the installation disc which gives the blue screen when booting. Can I run the test in safe mode?

michaelfengdayu said:

Insert the installation disk and power up while hold down the "D" key. It should go to the hardware test interface. If nothing happens, there might be some major problems in your computer. I suggest having a technician look at it.

PS: Make sure you use the original installation disk that came with the computer, not the Snow Leopard disk you bought later on.

Click to expand...

Thank you for the tip again. I found the original system disk and passed the hardware test. I also pressed "C" when restarting after the test, and surprisingly it worked. Right now I am installing the original system, and I will see if this will resolve the problem.

Thanks for all you guys' help.

Well, it passed the hardware test but the installation failed. I guess I have no other choice besides take it back to the genius bar.

I am running the extended hardware test in loop mode now because I am little suspicious about the accuracy of past tests. The tests I ran were pretty fast. They took about 2-4 minuets only, and the testing message under the progress meter bar only showed memory and logic board. Does anyone know what the test result looks like?

michaelfengdayu said:

Your problem sounds a lot like my 4 yr old iBook when after I installed the system it hang up right before the welcome screen. More likely a graphic card problem. If it is the NVidia 8600GT, chances are you are still covered under warranty. BTW, which country are you in? the Genius you described doesn't sound very professional and they don't do a flat rate repair normally.

Click to expand...

Really? Interesting. I'm in the U.S.. Well, I don't even know what the real problem is now, how can I convince them the problem is the video card?

I think that I do have video card related problem. After rebooting many times, I successfully login to Snow Leopard twice. however, both times ended in frozen screen not long after the login, and I notice there was a shadow of black lines under the mouse cursor. Can someone conform this for me? also, if it's the video card problem, is $310 flat rate a good deal to fix it (I don't have the Nvidia card)?

michaelfengdayu said:

Go find another Genius, and they should be able to find what the problem is. By law, they have to provide support to the product.

Click to expand...

I think that I do have video card related problem. After rebooting many times, I successfully login to Snow Leopard twice. however, both times ended in frozen screen not long after the login, and I notice there was a shadow of black lines under the mouse cursor. Can someone conform this for me? also, if it's the video card problem, is $310 flat rate a good deal to fix it (I don't have the Nvidia card)?