I have just completed configuring a Vista Business Virtual PC with VS2008. I installed VWG Community 6.1.2, VWG Silverlight 6.1.2 and Silverlight 2 Beta 2 Developer.
I then created a Silverlight application with a single Form1.cs containing a single button, set the Project Properties Web Tab Specific Page to Form1.swgx, did a build of the project and responded to the VWG Silverlight Packager. The debug run of that build produced the ThemeManager exception as before.
I then closed VS2008 and installed the Silverlight Tools for VS2008 Beta 2. Then opened the previously built project and did another build. The debug run of that build produced the ThemeManager exception as before.
I then created another Silverlight application with a single Form1.cs containing a single button, set the Project Properties Web Tab Specific Page to Form1.swgx. This time there was Silverlight Tab below the Web Tab. Then did a build of the project and responded to the VWG Silverlight Packager. The debug run of this build produced the form in the browser as it should be. PROBLEM SOLVED!!!
There must be something hosed in my XP SP2 installation of VS2008 that is causing the Silverlight Tools for VS2008 Beta 2 to fail. I am in the process of cleaning up that installation and will report back when finally successful.
I would like to thank Carlos (CHW), from this thread, and the rest of you for your assistance!