Pixelated screen followed by hard crash

Bit of a tricky one as I am troubleshooting this from range but was hoping for some opinions from everyone here. Sisters computer is on the fritz. It is a recent build of a core i3, 4 GB Corsair RAM, Sapphire 4??0 GPU, Corsair 500W PSU and the mandatory cd/dvd plus HDD (oh, and Windows 7 Home Premium 64 bit). Has not exactly been perfectly stable but a lot of the issues seemed to be with having her old XP harddisk connected at the same time. Took me a long time to work out what was crashing before realising it was the XP screen she was talking about not the Windows 7 one!

So, according to the description of what went wrong she was playing the Sims 2 when the screen went all pixelated and then it crashed. Upon reboot it would not go past the usual bios screen, though it did still beep as normal. Was a touch distracted by the beep thinking that that was the post beep code for bad RAM so I talked her through removing a stick of RAM and trying again. It then booted fine. Shutdown and added the stick back in again just to test and annoyingly it booted fine. So it does not appear to immediately be the RAM. Happy it was booting I left her to it only to get a call a few minutes later that it had had the same crash as before (pixelated screen). Though possibly it may be the graphics card so had her take that out and check for dust in the fins, make sure the fan would spin and that there was no obvious damage. Reseated it back in and it booted to a windows recovery mode. Decided a System restore would be good as there were probably some corrupted files and was wondering if a driver update might have caused it. During the restore it blue screened with IRQ_LESS_OR_EQUAL_TO with STOP code 0x0000000A.

All in all it is not looking good. My worry is that the GPU has gone though without a full mem test I would be unsure. Does anyone hav any thoughts or have they seen this pixel screen of death before as I must admit I havent?

EDIT: Well I finally got over to my sisters to have a look. Ran a memtest and my word, serious errors. think this may be the root cause of all the failures. One would suppose if the driver info is stored in RAM at any stage it could cause it to balls up quite spectacularly. still have to RMA it first and then will proceed further. thanks again for all the input.

The fact that the screen goes pixelated before the crash would tend to indicate graphics card problems.

Does the motherboard have integrated graphics? If it does get your sister to remove the Sapphire graphics card and use the motherboard graphics. While she may not be able to play the Sims it will allow the system restore to complete and let you run other diagnostics.

You then need to check the card out possibly by putting in another machine and repeating the same sequence that caused the problem in the first place. If the card is still under warranty then take/send it back to the shop and get a replacement.