Problem with roaming profiles – server 2000 and windows 2000 clients

Hi,

I have 2000 server and 2000 clients. (log on server is NT) I have roaming profiles set up. About 2 weeks ago, roaming profiles stopped working for every user (circa 50) The error on client is : windows cannot locate your roaming profile on XXX, you will be logged on with a local profile.. No changes have been made and the correct permissions is on profiles folder. Any ideas?? URGENT THANKS