A simple way to debug some .net applications without having the original source code. Requires Visual C++ It's available as part of VS2008 express (894.7 mb) http://download.microsoft.com/downl...6AA-CE894CBBB3DC/VS2008ExpressENUX1397868.iso Why 2008? It's free, no expiration, and no registration. This allows debugging at the level of il code. Put application in its own folder. C:\myfolder\interesting.exe Use visual Studio command prompt to dissemble the exe. paste this command at the prompt: ildasm C:\myfolder\interesting.exe /OUTPUT=C:\myfolder\interesting.il Now re-compile as debug: ilasm /debug C:\myfolder\interesting.il /OUTPUT=C:\myfolder\interesting_dbg.exe Close command prompt window. Open Visual C++ (original source language doesn't matter) Choose Open Project/Solution Choose your debug exe After it opens, select file-> open-> file-> choose interesting.il Now you can set breakpoints and start debugging. After staring at lines of code a useful option is under Tools -> Options choose Debugging ->General click the box next to Highlight entire source line for breakpoints and current statement.