M1330 Fingerprint reader problems

Starting a new thread for the problem I first mentioned at http://forum.notebookreview.com/showpost.php?p=2307702&postcount=827

From a web search it sounds like I am the only person to have come across it but I am hoping someone else sees the problem too and finds the resolution!

At Login screen I sometimes start to get the message:

"Please connect the fingerprint reader".

and when trying to use the fingerprint sensor via it's Control Center"

"Cannot enroll user.
Fingerprint sensor device is exclusively used by another application.

0xe7210000 Fingerprint sensor device is exclusively used by another application."

I am not sure what gets it into this state. I suspect it is could be connected with parental controls (perhaps it is locked to the child's account which is currently time-locked), or it is connected to adding/removing USB devices.
When this happens if I manually log back into the various logged in user accounts I find one in which it does work still work. In task manager I can see three psqltray processes running for the tray icon and three upeksvr processes.

 

and I just discovered that to get the fingerprint reader back into action (without rebooting) one should log off the user it is locked by. Then it seemed to work for the first user I switched to but not the second.

 

See also thread at: http://forum.notebookreview.com/showthread.php?t=167382