Last week's security update for Internet Explorer has left some users testing the beta of IE 7 with what Microsoft called "odd browser behavior," the company acknowledged Friday.

Users who had installed the beta of IE 7 alongside IE 6, then updated the latter with the patch provided Tuesday, Dec. 13, experienced browser "hangs," blank pages, and multiple windows that opened for no reason, wrote Jeremy Dallman, project manager for IE security, on the team's official blog.

One IE 7 beta tester reported that 100 or more windows would open in just seconds, while another wrote that typing any URL into IE launched his copy of Firefox instead.

Calling a side-by-side installation of IE 6 and IE 7 "unsupported," Dallman offered up a fix that involved deleting a key from the Windows Registry. Those users who want to stick with IE 7 should "uninstall and reinstall [it] in the recommended manner," which means overwriting the existing IE 6 install.

IE 7 is scheduled to move into a public beta in the first quarter of 2006.