What format are you saving in? Have you tried different formats (like JPG output)? If you do JPG output I suggest creating a folder -- don't save it to your desktop or you'll have too many files there.
What size is your stage (which sets the output resolution)?
I suggest trying a 320x240 project and see if that saves correctly. If it does, then the problem is probably with pIllusionRender (pIRender) the app that does the render if it's too large to be done inside particleIllusion itself.
Alan.
http://www.wondertouch.com