From Chris Adams:
This is a problem caused by the change between Beta 1 and Beta 2.
To fix, check the following 3 regkeys -
HKEY_CLASSES_ROOT\CLSID\{7D23CCC6-A390-406E-AB67-2F8B7558F6F6}\InprocServer32
HKEY_CLASSES_ROOT\CLSID\{FD5CD8B1-6FE0-44F3-BBFB-65E3655B096E} \InprocServer32
HKEY_CLASSES_ROOT\CLSID\{FEDB2179-2335-48F0-AA28-5CDA35A2B36D}\InprocServer32
Under (expand) InProcServer32, look for the presence of a non-2.0.0.0 (example 2.0.36.0) and remove it.
It has a reference that causes this to break.
If you do not have this MMC interface, you can use aspnet_regiis.exe
aspnet_regiis -s <path> where path equals the location in the metabase where you want the mappings to change.
Note: There is also a switch to do this non-recurvisely if you desire.