We started to see a rash of complaints from users who were encountering a black screen after logging onto their Windows 7 workstations. Except for the mouse cursor nothing else was functional, even the Task Manager couldn’t be started.
Most often this was encountered at the first logon of the day after the workstation has been logged out of the previous day and then left idle for several hours. Recovery required that a hard reboot was performed, and afterwards the user could logon normally. I actually encountered this a few times on one of my test workstations and a review of the event logs reveals the following warning message: “The wnlogon notification subscriber < GPClient > is taking too long to handle the event notification event (StartShell).”
I’m assuming the StartShell is explorer.exe. In a couple cases, if I let it sit long enough, the desktop might load or the TM would launch, but the overall experience was plagued by various performance issues and errors. A corresponding event follows after 10 minutes: “The winlogon notification subscriber < GPClient > took 600 second(s) to handle the norification event (StartShell).”
A brief email to our Microsoft PFE was answered with possible hotfix described here: http://support.microsoft.com/kb/2590550. Results since applying to affected user workstations seems to be promising.
If this doesn’t apply to you, there is also a Mark Russinovich blog on a similar issue he was encountering due to inaccessible mapped drives.
And, finally, another MS Hotfix-KB that you may also want to take examine: http://support.microsoft.com/kb/2525332