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If you install .NET Framework 1.1 you can then go into the IIS Manager and disable its usage. ...
Go to C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727 on the server and do:
aspnet_regiis -i
to re-register .NET Framework 2.0
and go to:
C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322
and do aspnet_regiis -u
to uninstall asp.net 2.0
and then launch the IIS Manager and you shouldn't see any asp.net 1.1 stuff there and the BES manager should launch ...
sounds good in theory at least