Vista's new reliability monitor is kind of great when you want check on your computer's overall performance. You get an index from 0 to 10 giving an overall performance rating of the system, which seems to be pretty accurate for what I can tell so far. It tracks hardware failures, software failures, windows failures, software (un)installs and some other failures, then gives you an index based on that info.
Actually, on a developer machine, this is a little biaised because any exception you raise from any of your program ends up lowering the index. That should invite you not to let unhandled exceptions exiting your programs... :)
Anyway, a few days ago, I went to look at that index and found that the only history I had was on the 01/01/1970... Rings any bell ? :)
Well, if you ever encounter this particular problem in case vista's not detecting that by itself and resets its database, just go there :
and remove the two directories that should be there. The Reliability monitor should detect it and restart just fine.