Visual Studio builds the entire solution when I exit debug mode.
This is very annoying as the solution contains 42 projects (ASP.NET MVC, IIS hosted WCF, Silverlight apps and others) and the build process locks Visual Studio for aprox. 30 seconds.
What causes Visual Studio to do a full rebuild of the solution? Is there a setting that I can turn on to determine the root of the problem?
Are you editing the source code during debugging?
VS does a "temporary"* compile in these cases to let you carry on running the program. Once you exit debug mode it knows this and can do a full rebuild of the project.
If you're going to do further changes then this build is a waste of time. Have you looked at the options on Tools > Options > Debugging > Edit and Continue? There's an option called Relink code changes after debugging and it's enabled by default. Try turning that off.
* this is the wrong term, but I can't remember the correct one at the moment.
I had the same problem. Today I disabled whole "Edit and Continue" option and annoying recompilation hasn't occured since then.