Reading the earlier threads, a number of people lost data. It seems XP released a security patch last night and forced a reboot on all computers. Gotta think that's the common denominator.
My boxes are all running Linux. I don't have a single Windows box booted. I really do not believe it's an instability in the machines. The systems were still running, and appeared to be stable when I found them. I've run other software for weeks on end with these machines, and have never experienced this sort of problem.