I was trying to install Visual Studio 2008 SP1 on my machine and I encountered this issue.
I looked it up, it looks like IIS Worker Process is some kind of w3wp.exe, so I looked into my Windows Task Manager and found out w3wp.exe is not running. I also took a look at my Worker Processes in IIS Manager and it wasn't started either. So, how do I close this application so I can continue my install or is there something else I can do?