Because of an update error in beta build 3604 of Microsoft Windows .NET, Microsoft has rereleased to its beta testers this version with a bug fix. "There is a known issue in build 3604 where certain warnings in the upgrade report will actually result in a blocked upgrade. This does not affect clean installs and doesn't affect all upgrades, only ones where certain warnings are generated in the upgrade report. You can workaround this issue by using the WINNT32 command with a /UNATTEND switch to do the upgrade."
News source: Active Win