Are you running it from Visual Studio with a debugger or from a built exe file? If you are not using a debugger, try attaching one and see what it says. You can also take a look in the system log to try to find more details on what caused the problem.
Some other questions that I have:
- What version of the .Net framework are you using?
- Are you building it on XP or Windows 7?
- Are the right frameworks installed and enabled on all computers? If the framework that you are using is disabled in Win7 by default, that might explain the problem.