Thank you for your help.
As it turns out my computer indeed had a virus (a fake msupdate.exe). My usual Antivirus programs couldn't detect it, but SuperAnti Spyware found it. The virus had been in the system for quite some time.  I don't know yet if the problem is over. I think I am going to reinstall psp9 and some other programs, just to be sure.

-Morbo will now introduce the candidates - Puny Human Number One, Puny Human Number Two, and Morbo's good friend Richard Nixon.
-Life can be hilariously cruel