I'm trying to debug a .NET GUI. When I put the breakpoint in a part of the code, it doesn't seem to be triggered when the code is executed. If I try to remove the breakpoint and re-add it while the ap has run the code once (works fine if it hasn't been run), I get the following message from Visual Studio: "The following breakpoint cannot be set: At Form1.h, line 1639 The Common Language Runtime was unable to set the breakpoint." All I can think is that the line of code being executed uses an unmanaged method (it's an XML utility that uses STL). Could that be the cause? If so, how can I resolve it, I need to break into the code every time so I can see what's going wrong with it. :(

I'd be interested to see what happens when you move the code in question from the header to the .cpp file.

See if you can break before it steps into that function, and then step into the function it won't set a breakpoint at. See what happens and get back to us.