I’m not sure what you mean by “continually looping” — you can’t stop the playback?
Does this happen when you don’t load AVIs but work with the program for a while? How long are the AVIs? How many emitters are you adding? Are you working at high frame numbers? particleIllusion works best with shorter clips, as it often needs to recalculate all particles from frame 1 — if you’re working at frame 3000, that can drag your system down.
Alan.
http://www.wondertouch.com