Symantec SymSnap VSS Provider keeps stopping

I'm using System Recovery on SBS2003 and the VSS Provider keeps on stopping after every job. I have tried setting it to manual and automatic but it makes no difference. This problem developed in the last few months after several years of successful use. I have to manually start the service every morning.

When I check the service list it doesn't actually say 'stopped' but the entry is blank.

Many thanks