X1 - X3 oddity.

so I did get X2 but never installed it since I was waiting on my new studiocat. I installed X 3 on it thereby completely skipping X 2. Just recently I opened up a project I'd created on X 1 and it acts a little bit hinkey.
probably 3 out of 5 times during playback I get that audio dropout at just about the same place. I bounced one track down so I could eliminate the plugins and deleted a couple tracks I didn't need. Same dropout. When I hit start and it resumes OK.
The whole project is just about buttoned up so this isn't a killer but is that something that is expected going from one over to three?
Thanks
WSS