sophie.pid file being removed?

We have had an awful problem  for as long as I've worked here at the uni 
regarding sophies' sockets. I kept gettin ACL errors from exim because 
they werent available. I now think i know why its been happening. We 
update our definitions once an hour and hup the daemon, somehow womeway 
the sophie pid file randomly gets wiped, and so a new socket is started 
over the already existing one. Im right in saying this would tie it up 
and make it unavailable for scanning???

Anyone have a simliar priblem with the pid file??

Ronan