CUPERTIONO, CA – A security update to Apple Computer’s popular QuickTime media player software is being blamed for causing problems for some Mac OS X and Windows users.

People have reported a variety of glitches on discussion boards on Apple’s Web site. Mac OS X users appear to be having the most trouble, including deleted applications and files, unplayable movie files and the disappearance rights to use the professional version of QuickTime, according to postings on Apple’s support forum, CNET.Com reported.

Apple released the update, QuickTime 7.0.4, on Tuesday to fix a handful of serious security vulnerabilities. The flaws put computers running Microsoft’s Windows and Apple’s Mac OS X operating systems at risk of being commandeered by an outsider. An attacker could exploit the flaws by tricking the user into opening a malicious file.

Some who installed the new version of QuickTime on Windows PCs say the media player is having trouble connecting to the Internet after installing the update. Other Windows users report not being able to download the software at all when they use the update feature in QuickTime itself.

Apple has published a tool for Mac OS X users that removes the suspected culprit, QuickTime 7.0.4, and restores QuickTime 7.0.1, according to the Mac maker’s Web site. People in the forums also report that QuickTime 7.0.4 was pulled from Apple’s Web site for some time and then reposted.

An Apple representative was unable to respond to a request for comment.