I was debugging a Smart Client app today, trying to find out why I was getting a WebException on calling a Web Service located on another machine. In the catch{} block, VS2005 shows me this little gem.
First of all, EXCELLENT error debug messages, at least I was able to focus on the exact cause of the Web Service problem. "Requested registry access is now allowed."
Shortly I put the pieces together and remembered that the Web Service was writing messages to the Application Event Log and did not have the proper security for it. Changing the anonymous IIS user (was IUSR_server) and enabling impersonation in the web.config did the trick. The point was that I found excellent debugging messages in VS2005 which quickly helped me track down the problem.