The Problem At work, we recently upgraded to Visual C++ 2005 Service Pack 1 (SP1). At the same time, our application stopped working for some users. Everybody that had SP1 was able to run the application. Some people *without* SP1 were also able to run the application. My system (not SP1) could not run the application built by the newly upgraded SP1 build machines, so I tried to figure out why. I