Suggestions on programs to test stability?

I have a E6400 @ 2800, and I'd like to make sure it's reeeeeally stable. It seems to be stable in Prime95 and Orthos, although I've only been running them for 2 hours each.

BUT, I've been noticing some strange quirks, especially when It was clocked a little bit higher (which led me to lower my OC a bit). One time the system rebooted when a friend of mine added a shared folder for us in Live Messenger. One time the GUI of Windowsblinds was corrupted when I started it. And one time I got a crash when opening CPU-Z. I'm not sure this is due to overclocking (haven't had a single problem in a couple of days now) but it seems that it might have something to do with it.

So here's the question: What programs should I run to test the overall stability of the system? Not just math calculations... I need to test other things than the CPU & RAM as well.