Thanks for your responses. I really appreciate it.
The problem is that it says in AE (in preferences) that no compatible openGL card can be found. This is so even with no comps at all, just a blank project, as well as in projects with lots of comps and effects. And I do know that there are lots of problems with AE and openGL, but I am concerned that this may be a symptom of something worse, since a couple weeks ago, AE was able to see and use my video card. And I do have the latest drivers.
Also, I have started having sound problems as well. When I first open a project and start working, and I am working with comps that have sound, at first the RAM previews are fine (the audio renders immediately), but after maybe 15 minutes or 1/2 hour of working, the RAM previews bog down (if they have any audio) and when I click “RAM Preview”, AE just sits there for several minutes before the progress bar for the RAM Preview begins to move in the timeline. But if I disable sound in RAM Preview, then the problem ceases. And if I close AE and re-open it, the problem is gone, and RAM Previews work well again (with sound), but then again, in about 15 minutes to 1/2 an hour, the same problem is back…
Any help would be GREATLY appreciated. I have two major projects I am working on right now and it’s deadline fever!