For whatever reason, whenever I try to run Calctor (install goes through OK), I recieve a dialog from Microsoft saying that "Calctor has encountered a problem and needs to close. We are sorry for the inconvenience."

I'm guessing that this happens before your program is fully JIT-ted because it's not a regular .NET exception dialog box.

I tried running your other software (e.g. Screen Capture) and it works OK.

What's unique about Calctor (besides the underlying C# code)?