Error when I "Compare" 2 versions of a page

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This may be an easy fix but I am getting an error message when I click on 2 versions of a page in Edit Mode under Versions. The message reads:

Warning: system() [function.system]: No '..' components allowed in path in /vservers/completeinsu/htdocs/concrete/tools/versions.php on line 65

I followed the path back to line 65 and can't find the problem. Has anyone else had this issue or does anyone know how to resolve this issue?