Domain login very slow 10+ minutes

We are racking our brains trying to figure this problem out an are currently stuck!

Basically we are having issues with some users taking ages to log in in the mornings, some times up to 20 minutes, we have tried correcting this problem looking at a variety of methods, we have checked DNS (seems to be fine, although not my strongest point I will accept suggestions), checked network speed (seems fine), the users in question are not using roaming profiles and there are no policies pointing to unavailable mapped network drives.

This is now a major problem as so many users are complaining that they can make a cup of coffee before the computer logs on.

We had a similar issue where workstations were taking about 10 minutes to log in. However, if the network cable was unplugged and the PC rebooted then they logged in right away.

We found that the slow logons were caused by a printer driver that was being installed but which required user input, which obviously couldn't be provided because the user was not logged in yet.

Try turning on Verbose Welcome Screen in GPO. This might show you where the PC is getting stuck.

You may want to test the "BufferPolicyReads" registry setting. This setting is enabled by default in Windows 7, but needs to be specified for Windows XP.

http://support.microsoft.com/kb/319440

Key: HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

Value: BufferPolicyReads
Type: DWORD
Value: 1