Two problems may exist here. That blue screen you got that was issued at boot up is known as a stop code. Now, you may have noticed long numbers similar to this:
This stop code signifies a portion of the RAM that has corrupted. However, be thankful the RAM did corrupt. Certain spywares try to rewrite themselves my caching in the RAM as an executable script (a virulent script as some may know it). What will happen as a protection basis is the RAM will not allow certain sectors to be written to in order to stop a massive corruption across the sheet discharge plate.
In order to start the PC properly, you need to first discharge the RAM. First, unplug the PC. Then hold down the power button for 45 secs, then open the side panel and remove the CMOS battery for 20 secs while still holding down the power button. Then remove the RAM. Then put the RAM back in, battery back in, start the PC, and enter the BIOS. Hold down CTRL, ALT, A, then hit enter once. Then type this in EXACTLY as you see it:
Then hit enter. Let go of CTRL, ALT and A now. Then go into your RAM settings and correct any timings you need to correct. The sheet discharge protection should now be cleared and the transistor lockers will reopen to the locked sectors. Once you get into Windows in SAFE MODE WITH NETWORKING, go to this URL:
Download and RUN stinger on the PC, and get rid of anything it finds. Then go to this link and DL and RUN this:
RUN it and clean everything up. Now, here is the important part. The RAM is cleared, but the CPU L2 Cache can still be infected by a variant trojan virulent script. If this is the case, it can redownload without you even knowing. To clear the L2 cache in windows, hold down CTRL ALT and A together once again IN WINDOWS on the main desktop screen. Hit enter TWICE while holding them. Type 1010101 and hit enter TWICE. Release all keys. You are done. See if that fixes it.