In any case, after waiting for several minutes, I forced a reboot, and it got stuck again and again. In safe mode also. After several attempts I tried 'Use last known good configuration', and with that I was able to get Windows to load up, but it froze after logging on.
Do you think this strongly hints at hardware problems rather than something caused by malware, after all? I get crashes (not freezing, just immediate reboot) when opening certain applications at times (cd burner, SeaTools, Autoruns, Procmon etc.) I have ran WinDiag to check memory however, and SeaTools to check hard drives, and main drive was OK.
Ah well, I need to try to figure out how I can enable the boot screen and see if it will enable me to view the error-check.