AIX install - cannot logon to J2EE

I have just installed EP6 SR1 on AIX (well up to the WAS anyway) and everything seemed to work except I cannot logon to the J2EE with the Administrator user id and password.

I try http://myportserver.com:50000 and the J2EE start page appears but when I try the code examples I get a windows pop-up authentication and when I put in "Administrator" as my user id and my installation password I get no farther.....3 trys and an authentication error.

Any idea......I think it may be a network issue as we only have one port open and numerous firewalls.

Thanks

Patrick