Take a close look at the H&V resolution of the stills. They may be REALLY big, and your machine may not have sufficient memory to deal with them; three gigs is almost nothing in AE.
Other things to do that can help you cope:
• Turn off multiprocessing ("render multiple frames simultaneously"). You have nowhere near enough RAM to use it.
• Turn off Open GL acceleration for rendering.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA