I had some "fun" with Visual Studio at work this week too. Due to reasons I won't go into our network is not as good as it might be. Having made a few changes to a utility class I hit recompile only for IncrediBuild to decide it was only going to build on my machine. Since this change meant recompiling practically the entire project this was going to take a while. One of my colleagues suggested rebooting my machine just to see if I could get IncrediBuild into a more cooperative mood, so I did. I stopped the build, closed Visual Studio, restarted and hit compile. Immediately I got a C1902 error (Program database mismatch: please check your installation). I couldn't build anything. We tried just about everything to try and fix it, including reinstalling Visual Studio. Finally, just as we were waiting for tech. support to show up to completely rebuild the machine I thought to Google the error. Some of the hits were talking about mspdb80.dll, so I tried replacing it. Lo and behold everything started working again. Why on Earth a full uninstall and reinstall of Visual Studio didn't fix the problem I can't begin to guess.