MGE Site Administrator login

[BK1]

Hi,
after installing SP2 from TB 2010 the MGE Site administrator login doesn't work.
Authentication failed. Please enter a valid username and password.

The MG Studio 2010 connect to the site, but the changes can't be save:
http:///mapguide 2010 does not exist or internet connection has been lost.
Verify the site name and connection to the internet.

The TB WEB login runs and the workspace can be loaded
with another message.
Warning: Exception aoccurred in Ajax callback.

Thanks for any idea

BK1

Win 2003 Server with SP2 and TB2010.