I just spent two hours trying to figure out why a chunk of code was throwing exceptions when compiled and run from my command line application but similar code worked fine when running in Visual Studio. The problem turned out to be a bug in the .NET Framework's XslTransform class which existed in v1.0 of the .NET Framework but not v1.1. Since I was using Visual Studio.NET 2003 [which uses v1.1 of the .NET Framework] to run my test app but compiling my actual application with the compiler for v1.0 of the .NET Framework I wasn't actually doing an apples-for-apples comparison when running both apps.

I'm tempted to uninstall v1.0 of the .NET Framework from my machine so I don't end up with facing this problem again. What a waste of time.