"Wow, that's certainly one way to win the browser war," said Andrew Storms, director of security operations at nCircle Security.

Google told Chrome users that Microsoft incorrectly marked the browser as malware.

Storms was referring to the battle between Microsoft's Internet Explorer (IE) and rivals, including Chrome, for usage share. According to data from one Web metrics firm, as the second-most-popular browser by the end of this year, pitting Google and Microsoft for the top spot.

Chrome users began reporting the specious detection of the browser early Friday in a on a Google support forum.

"This morning, after I started up the PC, a Windows Security box popped up and said I had a Security Problem that needed to be removed," said someone identified as "chasd harris" in the first message of the thread. "I clicked the Details button and saw that it was 'PWS:Win32/Zbot.' I clicked the Remove button and restarted my PC. Now I do not have Chrome. It has been removed or uninstalled."