Jittery Timeline

OK. I have a rule about never upgrading software during a project.
But I just broke it. Accidentally.
Footage is R3d - Transferred to ProRes HQ. All is good, rough cut looking f-ing sweet. Plays like butter.
Drive is a western Digital connected via SATA
Timeline:
2048x1024 - ProRes 422 HQ

I took a break and upgraded iTunes. And accidentally upgraded FCP to 6.0.6.
Now it plays all jumpy in the timeline. WTF?

I have been searching online for an hour on how to fix. No real luck.

Please help. Thank you very much.