R – Why does the Service crash at DebugBreak() on Vista

You probably are after something like this:

if(System.Diagnostics.Debugger.IsAttached)
  System.Diagnostics.Debugger.Break();

Of course that will still get compiled in a Release build. If you want it to behave more like the Debug object where the code simply doesn't exist in a Release build, then you could do something like this:

    // Conditional("Debug") means that calls to DebugBreak will only be
    // compiled when Debug is defined. DebugBreak will still be compiled
    // even in release mode, but the #if eliminates the code within it.
    // DebuggerHidden is so that, when the break happens, the call stack
    // is at the caller rather than inside of DebugBreak.
    [DebuggerHidden]
    [Conditional("DEBUG")] 
    void DebugBreak()
    {
        if(System.Diagnostics.Debugger.IsAttached)
            System.Diagnostics.Debugger.Break();
    }

Then add a call to it in your code.

I've done a little digging around, and I've found a couple of posts around that suggest you're not the only one suffering from this:

• http://developer.nvidia.com/forums/index.php?showtopic=318
• http://objectmix.com/xml-soap/115379-problem-latest-ms-patches-msxml4-vista.html

Particularly, the second one is of interest, where Tom Chm mentions:

We believe we have identified the root cause of our crash, and adding a virtual destructor to our interface class wrapper seems to resolve our problem. But we would like to know the exact cause of the crash to verify that we didn't just sweep the actual problem under the rug.

The problem may be with a destructor somewhere, or lack thereof. If you have a way of attaching a debugger and stepping through the shutdown process, it might be of help.

You might want to read through the whole thread and see if there's something you can learn. That is, if you haven't already found these posts in your searching, of course.