OS X.1 - Finder crashes after login



Here's what happened.
I had 10.0.4 running fine so I installed 5g48.
It ran great.
I then obtained and installed 5G59 and now the finder crashes after login.
I installed 5G64 over top of it and the problem still occurs.

After I login there is a long pause then the Finder appears. As soon as I move my mouse; or wait more than 5 seconds; the entire finder disappears and all I have left is the mouse on a blue screen.
Does anyone have any ideas on how I can fix this?!?
I might be way off, but you might try doing a clean reinstall of OS X 10.1, rather than installing over the top of previous versions. Just a thought.