Can be a few things as I've found out from past experience. Going by your setup it's probably not hardware.
So software, you can run snoop dos and have it write to a log file when you run whdload. You can also run whdload in debug mode by changing it in whdload.prefs
The other thing to do is to post your user-startup and startup-sequence.
Also what's running from wbstartup?
