Visual studio hangs when starting build for 15 seconds - what's happening?

I am Visual Studio 2008 Team Suite. Somewhen yesterday it started to hang for about 15 seconds when I start the build of my solution. During this time, the output from build doesn't show anything. After this time, it says

1>------ Build started: Project: MyProject_Test, Configuration: Debug Win32 ------

, and the build works normally.

So I wonder: what does Visual Studio do between selecting "Build Solution" 开发者_运维知识库and displaying the text above? This would help me track down the problem!

Thanks for any hints!