Arg! I have a custom \"harness\" executable running my class library project. Every time I step into the harness\'s code, I get that \"No Source Available\" pane popping up.
After finding no help on this, I dug in to it myself and fixed it by Hiding the WindowFrame in the event that it is shown. There is no visual refresh glitch that I've seen so far.
Here is the GUID for the "No Source Available" pane: {1820bae5-c385-4492-9de5-e35c9cf17b18}
I found most of what I needed from this post:
http://blogs.msdn.com/dr._ex/archive/2004/11/07/253601.aspx
I believe this will only affect solutions with this package loaded, but really I don't know if the package stays loaded/active if the related project is closed.