I have no idea.  The fact alone that rjay9663 is using a mac and having the same problem makes this a lot harder.  Riquelme8, for your system, I don't know, but my laptop is a Dell Latitude D610 without a video card.  I have only a hair more processor speed than you do, and it's never given me this problem before. 
Oh, since upgrading to 6.1, I haven't had that one problem, either.  You're problem could be anything from video cards, video drivers, something as easy as a bad object download, or possibly a certain object combination.  **
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