This was a curious matter. I installed Visual Studio 2010 on a machine that had VMWare Server running. The VS install went through a restart and installed just fine. When I tried to launch VMWare to access a VM through VMWare Web Access, the VMWare configuration site was not running. Turned out that the VMWare Host Agent (VMwareHostd) was not started (even though it was still set to startup Automatically)! I started that service and was able to access the VMWare config web site. This happened on two different dev machines, so some part of the VS install was being stubborn.