The first reported incident came from the Chrome help forums:
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. 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.
Microsoft, after updating the definitions, acknowledged and apologized for the mistake:
An incorrect detection for PWS:Win32/Zbot was identified and as a result, Google Chrome was inadvertently blocked and in some cases removed from customers PCs. We have already fixed the issue..., but approximately 3,000 customers were impacted.
Google, forced to act on the stupid mistake, placed a large red banner on its support pages reading "Alert: Google Chrome has been incorrectly marked as malware by Microsoft security software."
If you were affected, just download the update, reboot, and reinstall Chrome, says Microsoft.
Written by: Andre Yoskowitz @ 2 Oct 2011 22:22
