I'm having exactly the same trouble, though my system has been up and running for around a year and a half. It seems to me my problem started when I contracted a virus (from what source I don't know...I'm very careful about such).
I'm hoping Nemesis is wrong, but I'm getting to the point that I think that's going to be the only way to take care of the problem. I've tried a couple of Warm-Reinstalls and it didn't help, nor did anything else I've tried.
Good luck!