Commonly you are presented with a broken administration page at https://your CME server/ccme.html. You can find guides at Cisco.com or even your local CME html help page on troubleshooting setting up your HTTP server and authentication correctly, and how to copy the GUI components correctly.
If all else fails, check your ephone dn users. If you show run and find, for example:
username "user4900" password 4900
I suggest you remove all the usernames with no username "user4900" password 4900, etc. and the re add them using username username4900 password 4900.
I ran into this using the QCT with:
Software Version 12.4(11)XJ2 / CME 4.1(0)
Feature Package IP|FIREWALL|VOICE|PLUS|SSH
GUI Version 126.96.36.199 (Compatible with IOS 12.4(11)XJ)
Incidentally, after adding them again, the names still have quotes surrounding them, but the GUI works.