After using AE for a while, when I go to do a "0" render, the green bar goes about 2 seconds in, then the timeline starts to play. It repeats when it hits the 2 second mark. If I try to use the "zero" render again sometimes it just goes the two seconds, other times I get an error message like, "After effects needs at least 2 frames to render....". Something like that. If I restart AE usually the problem goes away. I have lots of ram on a new Dual Core Mac. Running Snow leopard, system 10.6.3.
The length of a ram preview depends on available ram, composition size, and work area. 2 seconds isn't unreasonable on CS4 for a 2K comp. If your work area is longer than 2 seconds try reducing the resolution of your comp to 50%.
Some project specs would help us diagnose the problem.
Thanks. I know what you're saying. But these are comps that would render in the timeline just fine... for a while. Then they start doing this 2 second thing, with no change in the timeline. A fairly heavy timeline usually will give me about 12 or 15 seconds of full render with audio.