vauxhall combo 1.7d 1998?

could possibly be that you are getting a hydraulic lock in one of your cylinders, when engine is hot and stopped - say after a run, if cooling system is pressurising by head gasket leaking then this pressure will force water into bore -so that when you try to start it locks giving sympton of flat battery.you could try straight after a run ,releasing pressure cap [take great care to avoid scalding] and after your 10 mins or so try to start ,if ok then you fault is probably as above.

k
May 2009