Scan log status is struck in Scanning state

Hi ,
Few of our Sep clients(windows server version 2003/2008/2012) are showing as "Scanning" under View Logs>Scan logs
They are struck in that state for the past few weeks.
We have tried to kill the process and restart them-no go
We have tried to stop the service and restart them-no go
We have tried to reboot the machine -no go
But for the above all clients they are having latest definitions up to date.
Also these clients are running with 12.1 RU6 MP7 (12.1.6 MP7)
We have Sepm console recently upgraded to 14 mp2.
Your suggestions and help are much appreciated..