I have a new HTC Advantage PDA which worked fine on Windows Mobile v5.0 out of the box until I installed and then uninstalled the included trial Tom Tom software.
At this point I found I couldn't connect to the web via WiFi or GPRS. Checking 'My Connection' in 'Settings' and reinserting my password and then clicking 'Finish' didn't seem to set my password. There would always be 16 asterisks showing in the password box as though the device had an embedded underlying password it was always using. The same would happen even after a hard reset - it would show an empty password box, I would insert my password, click Finish , go back and find the same 16 asterisks inserted again (my password is less than 16 letters).