I have a Vaio laptop, about two and a half years old. I haven't had many serious problems with it, but today it seems to have gone badly wrong somehow.
All of a sudden, as I was using it, a blue screen came up, reading:
Call your hardware vendor for support
NMI: Parity check/Memory Parity Error
The system has halted
All I could do was hold down the power button until it switched off. I then turned it back on in Safe Mode to find the display pretty messed up - colours wrong, lines across the screen etc. Also, I couldn't get it to start up normally, i.e. not Safe Mode. The first time I tried this, I got the same blue screen as before, but since then, it doesn't even get that far - it just restarts and tells me 'Windows failed to start'.
At first I was convinced this was the result of a virus (which I have still not ruled out) because earlier in the day I had clicked on obviously a bad website which had popped up with a download window (using Firefox by the way) asking me whether I wanted to download a file I think called 'flash-player-update.exe' and took me to some weird porn website in another tab. I closed the browser immediately and assumed the problem had gone, as I hadn't knowingly downloaded the virus. Also, I was running Norton 360 which I hoped would have told me if I'd picked something up.
Just in case, I also updated my Malwarebytes definitions but didn't run a scan. Once this problem had cropped up, I did do a full Malwarebytes scan in Safe Mode and it found nothing.
So I started looking on the internet on a different PC to find out what the problem could be... seems the most likely culprit is a bad video driver, so I uninstalled this and managed to get Windows to boot normally again, but after letting it reinstall the old driver and restarting, I had the same problem again. I then tried downloading a new driver from NVIDIA, which it claimed would suit my driver (NVIDIA GeForce 8400M GT) but when I tried to install it I was told it was could not find any compatible hardware.
I tried giving the old driver another go but no luck so I'm back to the original problem.
I also just gave the System Recovery Options 'Memory problem scanner' or whatever it's called a go, but this turned up nothing. I gave the repair option on the 'Windows failed to start' screen a go, but this just ended with the PC restarting suddenly - not sure if that's meant to happen.
Not sure if I've forgotten anything I've done, but if I remember something else I'll update this post.
There are still a few hints that it's virus related. One is the fact that when I start up the PC, immediately after the VAIO logo appears onscreen but before anything Windows-related appears, the screen is covered in identical characters, arranged in a tidy formation. These change every time I restart the PC, and have included 'c' with an accent underneath it (don't know how to write it on here) and most recently a little smilel face, which struck me as a very odd thing for the PC to mistakenly display. When no driver was installed, this was not displayed at startup.
On the other hand, I don't quite see the point of the virus if it is one. The display seems to be the only part obviously affected, as well as the inability to start properly obviously. Plus, when the original blue screen first appeared, I was watching the an online video in HD which I understand really tests the video card.
Sorry for the longwinded message, but I thought it would be good to include as much information as possible. Most similar problems I've found on forums have taken a long time to resolve, if indeed they have been resolved. Please help me if you have any ideas.