Thanks for posting!  Usually that happens when there is an underscore in the server name.  If you use the ip address instead of the server's name to get to OMSA, that will get you around the problem.  The OMSA install video at [URL] has more information and a more permanent fix.
3 PE2950 server A, B and C. A and B server's OS is  Windows Server 2003 x86 SP2, C's is  Windows Server 2008 x64 SP2. All Server installed OM_5.5.0_ManNode_A00 and 5.5.0.1 patch.  I input the correct OS administrator account and password in the  login page of OpenManager Server Administrator Website. A can enter program successfully but B and C cannot. No error output, just go back to the login page.  what's the possible reason for the failed logon? I appreciate for any suggestion.
Can't login to OpenManager Server Administrator Website