Yeah, I was afraid you'd copied that bit of docs -- it had a nasty but subtle bug in the jobHandle refcounting. The call to Vix_ReleaseHandle(jobHandle) in the VixDiscoveryProc() is bogus, and probably causing your crash (its overly decreffing that handle). Remove that line, and see if things get happier.
VMware server supports just once snapshot, and Vix enforces that.
The latest docs are at
http://pubs.vmware.com/vix-api/ReferenceGuide/
The functional reference does refer to things only available in the latest release, but each function should specify which release it works with.
