I really hadn't done more with V-Vocal than to just test it out on some vocal tracks.
It was always pretty buggy - though my recollections are that folks generally had found that it was best to do little bits of edits at a time with V-Vocal, than to go ahead and bounce them to 'print' them, as having too many active V-Vocal edits at a time, in a given project, was a good way to start causing problems and crashes.
Melodyne is the replacement that now ships with Platinum, and it is WAY more stable, in my opinion, as is Platinum versus X1, X2, or even X3.
But - yeah - if you are having V-Vocal nightmares, try doing smaller edit chunks at a time, and when you are happy with them, bounce them. That seemed to help me, as well as others, in my recollection.
Bob Bone