If you go to sign in on a computer on a domain and it is taking longer than usual or anything more than a minute, try these steps.
To Resolve: Edit
1. You want to look for network slowness first, many times this is a failing switch or break in communication between the workstation and the Domain Controller.
2. Go ahead and login. Once in, Run - regedit.
3. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
4. Create a DWORD and name it "verbosestatus" with a Data Value = 1.
5. Exit regedit and logoff the account. Now sign back in, I have seen this work multiple times.