I wonder if it is something similar to my recently replaced on warranty hard drive (after long on-line chats with Dell representatives, they finally agreed that it was hard drive problem and that they would replace it).
My drive was making a ticking noise, a sort of repeated "tick·tock", as that made by a clock. After that the system froze for some 30 seconds, then went dead, complete with the "blue screen of death". Sometimes it happened every few minutes, and sometimes only once every few days. A few times, closer to its end, it didn't want to boot after that, so a few times I had to use Windows CD to boot and repair the system. After that only Dell agreed to replace it.
Even though I had a complete backup, I installed XP and the software from scratch on the new drive I got - just in case.