I've had the same problems. I've been advised not to uninstall the newer version of .NET because MS Visual C++ Express Edition requires the newer version.
QUOTE (roxlabs @ Feb 11 2008, 09:54 AM)

We are planning on updating the retail and free versions of Buzz before the end of the month. In the meantime, if you uninstall .NET then install Buzz it should work. Sorry for the inconvenience. Microsoft threw us for a loop there - dealing with these .NET packs has taken a lot of work - we don't want to force people to go looking for the components so we try to install them using Microsoft's guidelines.