HELP, Enterprise manager does not work after upgrade to NT 4.0, HELP

After an upgrade to NT 4.0 I get the following error messages while starting the enterprise manager:

VOD
Failed to get local hostname

and after that

VOC-00002 Internal-error:
Failure to obtain interface (logon)

Then the enterprise manager crashes

Oracle says:

VOC-00002 Cause:
A call to GetIDsOfNames for the interface failed. There may be a mismatch between the calling process and the external server.

Ok, but what is the solution?

Help me, please!!!

-- 
Bart Breggeman