Something very odd is going on. It's been going on for some time, but I've just ignored it up to now. I have both a Silverlight and WCF service in my solution, which shares .CS file between them (one project has a link to the file, which exists in the other project). While debugging the Silverlight app, pressing the F10 key steps through code as normal, and when I get to a method call which exists in the shared file (between the projects), and Press F11, it simply skips the method instead of stepping into it (and yes, the "Just My Code" option is not checked). If I put a breakpoint in the method I'm trying to get into, it works fine (as in the debugger will break on the line), but as soon as I step (F10) it exits the method (and with F11 [step into] also).

Ok, on first thought, you might think it's to do with the link, but no, it isn't. I tried removing the link and using a copy instead, but the same thing happens. And no, it's not the debug symbols, I looked into that already.

The method I'm trying to step through is static, and is in a non-static partial class, in a file shared by both projects.

My guess: The same types and static methods exist in the WCF and Silverlight ... would the debugger get confused?