One cause of this problem is: the user try to kill the edpa.exe process more then ten times.
The wdp process will stop trying to restart the edpa process after ten tries. This is by design. There is no way for wdp to determine if edpa was killed by a user or if it has crashed. In order to avoid constant restarts due to unrecoverable edpa crashes, the DLP agent limit the number of restarts to ten if edpa restarts happen within a short period of time. After the tenth time, wdp backs off for several minutes before trying to restart edpa again.
But, I really suggest you to log a TS case for support. Not all the DLP agents encounter this problem in your customer's environment, so, may be this is a compatibility issue on the agent.