I am running ZCM 10.3 on a windows 2008 r2 server. A few times a day the preboot service stops. We can manually restart it or reboot then it works for a bit.
the event viewer shows

Faulting application name: novell-pbserv.exe, version:, time stamp: 0x4b99e536
Faulting module name: zenimgweb.dll, version:, time stamp: 0x4b99e528
Exception code: 0xc0000005
Fault offset: 0x000011bc
Faulting process id: 0x95c
Faulting application start time: 0x01cb031f56d96c2e
Faulting application path: C:\Program Files (x86)\Novell\ZENworks\bin\preboot\novell-pbserv.exe
Faulting module path: C:\Program Files (x86)\Novell\ZENworks\bin\preboot\zenimgweb.dll
Report Id: 11f2d8de-6f13-11df-b805-001e4f3ff45a