Garmin MapSource question

I installed the Garmin MapSource program that came with my new GPS, and had no problems with it.

Then I installed the Garmin US TOPO 2008 mapset (which I think installs over the old, standalone app). This worked fine for a day or so, then yesterday when I went to launch it, it crashed on launch, with a message to reinstall the program. This I did, uninstalling the old, and reinstalling the new. I did this with both the TOPO program and the original, and everything I try gives me the same error on launch.

Anyone have this problem before?