Fortinet Terminal Server client services needs to be restarted daily

Dear all,

We have a 60D. FSSO and TS agent configured on AD Server. FSSo users gets authenticated fine, but everyday we have to restart the TS Client service, then only the Terminal users(RDP users) gets authenticated on fortigate. We changed the "Log ON" information in the TS Client service properties to AD-server\Administrator, so that the service works with Domain admin privileges, but same issue persists. 

Any idea, how to debug/troubleshoot this issue?