I have this same problem on the same computer, except I have over 700 MB RAM. So far, Adobe has no explanation or solution.
#1
Is this the problem you're having?
Martin Sammtleben, "Can't use PSE 3.0 Mac if PDF graphic clip from OS X Preview is on the clipboard." #10, 2 Feb 2005 8:37 am </cgi-bin/webx?13/9>
It sounds like a bug.
#2