All programs shutting down

A problem developed sometime last night where almost every program encounters a serious error within a few minutes of starting and crashes. Firefox repeatedly crashes, as does Internet explorer. Windows Media player won't play, and I tried to run SpyBot but there was an error in every check (something about a pointer error?). These problems were occurring even in safe mode. I will give more specifics if you need them, but I wanted to keep this message short because I don't know if it's going to continue to crash.

Everything ran fine until yesterday evening and I didn't install any new programs since then, so I'm very confused.