I am starting to have a problem that I do not understand what could be causing it. Randomly on the computers on our network the users will have to enter their IDs and passwords in order to access their email and/or the drives on our network server. Normally once you sign into the computer using your network ID and password the networks drives and access to their email does not require any additional enter of their IDs or password. The thing that is puzzling me is that it seems to be random, different computers, different user, at various times. Does anyone have any ideas as to what I could look at to see what may be causing this. We also use three different OS, XP, 7 & 8. It does not seemed to be associated with the operating system because all the various operating systems have this problem.