Siemens SpeedStream 4200 (13A4200001) Bridge "ghost flushing" Questions

Ghost flush on toilet bowl I am regularly getting 'ghost flush' on my toilet tank. I close the tap on the tank to avoid listening to the flush throughout the day and night. How do I go about resolving

...ghost flushing about every ten minutes. It does not flush but runs for about five seconds then is fine. ideas? It was installed six months ago by a plumber and only started doing this one month ago. ...