Receive prompt’s for Password/Domain

I have three computers that all of a sudden are having the same problem. When they try to open Microsoft Outlook they are being prompted for Username/Domain/Password – and it will not except the password, they cannot access there email what so ever. They keep getting login credential incorrect. The only thing that was done the night before this started happening was all updates on the server were done.

We are useing Microsoft exchange server 2000 on a windows 2000 server.

One computer is XP and the other two are 98.

I have tried everything I can think of…Please help!

What doesnt make sense are all are computers are set up the same and only these three are having the problem.