Remote debugger causing visual studio 2008 to exist debug mode

Question

A very strange problem - I have two machines, Local and Remote. Remote is running Visual Studio (2008) Remote Debugging Monitor.

I develop on Local, then during build VS copies the necessary files to Remote. I then press F5 and Remote starts running my code. Breakpoints allow me to access the debugger on Local, single step the code etc. All working perfectly.

Or, should I say, was working perfectly.

After a massive code change I was debugging the code, when suddenly I found myself back in edit mode. The application on Remote was still running. It took me a lot of time to accept what I was seeing - I never had VS turn from debugging to edit mode all by itself when single stepping the code. I'm used to bugs in my code, but this is a problem in the environment! I don't know how to fix this.

Single Stepping through the code I saw that the problem always appears at a fixed location.

    module A: string s = moduleB.FuncA();

Then, at module B:

        public string FuncA()
        {
            return FuncB();
        }
        string FuncB()
        {
            Logger.LogInfo("FuncB");

When calling ModuleB.FuncA from ModuleA, the debugger took ages to step till the opening bracket '{' of FuncA. Then pressing F11 once again caused the local VS to change to edit mode.

Running the code on Remote (i.e. with VS installed on Remote, and using a local debugger) works like a charm.

Any ideas?

(P.S. both Local and Remote runs Server 2003 R2 SP2.