Groveler errors

On my RIS server in the Application log I’m getting a Groveler Error EventID 12292 (groveler has failed due to a database error) every few hours (as little as 4, as many as 11 hours apart). The error is followed about 30 seconds later by a grovel stop and a grovel start, and in another 5 seconds a Groveler Warning EventID 8194 (USN log overrun).

How can I get rid of this persistent error?