Integrated Logon Suddenly Not Working for Some Users who Changed Network Credentials

We are on on Service Desk 7.4 and recently converted several temporary staff to permanent staff. When we do that it changes the network logon ID.

I have updated the ID in Service Desk, and have done so in Active Directory but two of the staff are now getting "integrated logon not working" messages, even though they have successfully logged many calls before the change in network ID.

We have compared the credentials in Service Desk and in AD and they appears to be correct and the same. We have cleared out the IE cache, but nothing seems to work. Any suggestions will be appreciated.

Mark