Visual Studio Debugging Madness!

I am having some really weird stuff happening with my co-workers Visual Studio.

We are totally stumped and I am just throwing this out there in the hopes that someone has a good idea.

Here is the issue:

He has some code that runs on a timer. In that timer, he does a lock to ensure that only one "thread" at a time can get in.

He puts a break point on a spot inside the lock and runs to that point.

This is where the weirdness happens. As he is stepping, the flow will jump him back to that break point after a second or two. It is very confusing. The thread ID never changes, so it is not a new thread that is getting past the lock somehow.

But here is the really weird part. It happens every time for him, but when I download the source 开发者_如何学Cand try it, it works just fine for me. I can step through all the code and I never get my next statement "jumping around" (for lack of a better word).

The only difference between his machine and mind is that I have Visual Studio 2010 installed and he does not. (However, we are both running this in Visual Studio 2008 SP1)

Any ideas? any at all? I am really stumped.

The first thing that comes to my mind is this hotfix:

http://support.microsoft.com/kb/957912

And if I remember right from about 2 years ago, installing the Silverlight SDK also fixed the issue. I remember thinking that was really strange, but it did the trick for me. (I actually found that solution before the hotfix)