Microsoft Corp. confirmed today that it is investigating reports that a security update for Internet Explorer issued last week has crippled some users' ability to get on the Web with the browser. Users started posting messages to multiple Microsoft support newsgroups almost immediately after Microsoft released the MS07-069 security bulletin on Dec. 11, saying that they were unable to connect to the Internet, either because IE refused to open or because when it did open, it could not reach various sites.

"About 60% of the time, I would get an 'Internet Explorer has encountered a problem and must close' dialog," reported Bill Drake on the Windows Update newsgroup. Others echoed those comments on IE-specific forums, noting that both IE6 and IE7 balked at loading, or while loading, some pages, particularly home pages, on both Windows XP and Windows Vista machines. Harold Decker, operations manager at San Diego-based Gold Peak Industries NA Inc., started fielding calls from users last Wednesday morning as soon as people hit the office. "I stopped everyone who hadn't installed the update from installing it, after four PCs out of 14 had the problem," said Decker, who manages a total of 35 Windows XP SP2 machines. "We're a pretty plain shop; all our systems run Windows XP SP2 and IE6," said Decker. "But some kept crashing. It seemed limited to the window that was opened, and changing the home page to something simple, like a blank page, gave a better success rate."  Decker cited numerous brand-name sites that workers at Gold Peak couldn't reach without crashing IE, including Federal Express' and Lowe's Home Improvements.

Microsoft said it is on the case. "Our customer service and support teams are investigating public claims of a deployment issue with Microsoft Security Bulletin MS07-069," Microsoft's Mark Miller, director of security response, acknowledged in an e-mail. "If necessary, Microsoft will update the Knowledge Base article associated with MS07-069 with detailed guidance on how to prevent or address these deployment issues," Miller added. Other users on the support forums weren't much help, except to suggest uninstalling last Tuesday's security update. That's what Decker did. "We uninstalled [MS07-069] and have had no problems since then," he said.

Update: Check out this "Internet Explorer 6 crashes after you install security update 942615 on a computer that is running Windows XP Service Pack 2" official post.