I had to RMA a 2600 that was doing weird shit like that. Hanging, freezing up, having to hard reset a couple times a day. and I tried all of the BIOS voodoo I could think of to fix it, reinstalled windows, stuck the CPU in another board, tried different ram. I believe you get a 3 year warranty. I honestly do not think they even looked at my CPU, I had it delivered to them one day, and they were shipping out a replacement the next.
The thing that did seem to help was turning off automatic voltage and setting it manually and some other stuff, basically crap I should not have to do to "fix" a problem.