Less than three weeks after Apple Computer issued an update to patch four security flaws in its QuickTime media player, <A HREF="http://news.zdnet.com/2100-1009_22-5940081.html?tag=zdnn.alert">a new "critical" problem</A> has been discovered. The unpatched vulnerability could allow remote execution of code, according to an advisory published Monday by eEye Digital Security. It affects various versions of Apple QuickTime running on all types of operating systems, the company said, but did not specify which versions in particular were at risk.