My sony vaio has a black screen that flashes the words to reboot by pushing "F12". I am having problems to reboot it. I also think it has a serious virus or etc.. I have tried numerous things, but can not understand how to fix it or what needs to be done. Can anyone please shed some light on what to do? Thanks!
Try booting into safe mode with networking (in case you need to download something). Run AV scan and malware scans. If anything is detected in safemode, repeat those scans once you boot into normal mode.
You might also have to boot with windows CD and do an inplace repair install of the OS.