Microsoft Visual Studio Unable to break execution

I had been working on a C# project for some time now. When I try to debug the C# project code, in Microsoft Visual Studio 2005 I get an error message.
I recently had a virus infection because of which, I cleaned up my machine. I guess there could be some files related to MS Visual Studio. I am able to run the other entire projects fine, since their code is built in C++.
Thanks for your help.
Microsoft Visual Studio
Unable to break execution. This process is not currently executing
the type of code that you selected to debug.
