PS: My computer has a dual core pentium processor with 1G of ram which is adequate for this project.
Not necessarily.
Coupled with the buffer to playback whatever else might be on the timeline, it may well be that you’re eating the available RAM. Particularly if you’re using 3D TM.
Nested veg files perform differently on various machines. YMMV. Of course, your project will render correctly, but that doesn’t help much w/Preview. SHIFT+B will render to RAM
Douglas Spotted Eagle
VASST
Certified Sony Vegas Trainer
Aerial Camera/Instructor