domain problem.

I hope someone can help with a strange problem.

I have a windows 2003Std dc running ad and dns supporting about 20 users
running winXP pro and am having severe issues when it comesx to user logons.

When i tried to logon to the server from a client pc the logon seemed to
take forever and when it did eventually logon an error popped up saying that
they couldnt access there desktop(stored on the server as a roaming
profile(server\profiles) and folder redirection(server\Users).

This has been working perfectly for about 2 years now and has just suddenly
stopped working.

I have checked dns on the server and all is well, the clients have the
server set as there primary dns server.

I am able to logon to the domain at the server and also connect to the
internet at the server but cannot do either at the client Pc`s.

I have run dcdiag and netdiag and there are no errors.

I can ping the server by IP address and name from the client pc`s and can
also connect to the administrative share (c$) on the server from the clients.

Don`t know what else to try so am looking to the experts for help.

Thanks in advance
Gareth