Error, Unable to debug

I've imported a project made in Visual Studio.NET 2003
then trying to debug i just recieve an error message:

Error while trying to run project: Unable to debug
binding reference (handle) is invalid.

The program (A C# windows application)runs great if i run without debugging, every single part work! That's confusing me!

I'm new on this, so please help me if you have any idea!

[396 byte] By [mackan100] at [2007-12-17]