Audio and Video drift in timeline with FC6.0.6

So suddenly every project I work on with my imac has an audio and video sync problem. I can see the video become jittery for a second then it will line up correctly. Sometimes it never lines up. I see audio events in the timeline and hear the event late. If I export it out it lines up correctly. In the timeline it is inconsistent. This makes it impossible to line things up.
This happens with imported camera footage as well as After Effect exports.
I tried changing my sequence settings around and it actually works correctly for a few minutes then starts lagging again.

Computer Info:

Model Name: iMac
Model Identifier: iMac9,1
Processor Name: Intel Core 2 Duo
Processor Speed: 3.06 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz

Running 10.6.8

Footage is all rendered out Apple Pro Res 422. It does the lag thing with DV footage as well. I have NOT changed the way I edit and record. I have been working with FCP for 3 years and this is something new. The sequence is set to match the footage.