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As far as I can remember it only happens when I have rhino open..and usually multiple windows open with heavy 200mb+ files. However, when I close rhino it doesn't go away until restart.

Most likely a problem with Rhino graphic driver. It's a beta version, you can't complain about this kind of problem. The best thing you can do is to contact Mcneel and report about this issue.
 
Most likely a problem with Rhino graphic driver. It's a beta version, you can't complain about this kind of problem. The best thing you can do is to contact Mcneel and report about this issue.

Obviously it isn't limited to Rhino based on earlier posts that attribute a similar (if not identical) problem to Safari and Mavericks.
 
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