Debugger problem "The breakpoint will not currently be hit. No symbols have been loaded for this document"

Got this message while trying to debug a web service in VS2008: "The breakpoint will not currently be hit. No symbols have been loaded for this document."
Found that the following (from comments here) fixed it for me:

"If you are using the vb profile, then when you hit F5 you will get a debug build, but if you hit build you will get a retail executable. The simplest way to get things working again is to go to delete the bin directory under the solution/project path and then hit F5 again."