"I have been using Chrome on my office PC for over a year. 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," commented one of the users. "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. The Chrome.exe file is gone. Was there really a problem, or is this just a way for Microsoft to stick it to Google? If I reinstall Chrome, will it have my bookmarks and other settings? Not sure what to do about this, but I much prefer Chrome to Explorer."
Other users have piped up to confirm that Security Essentials is definitely blocking attempts to reinstall the Google browser and identifying the file as the infamous data-stealing Trojan.
Ryan Naraine says that Microsoft Forefront Endpoint Protection has also started behaving that way, and has attributed it to the fact that both solution share the same anti-malware engine.
UPDATE: "We have already fixed the issue -- we released an updated signature (1.113.672.0) at 9:57 a.m. PDT -- but approximately 3,000 customers were impacted," said Microsoft in a statement regarding the issue. "Affected customers should manually update Microsoft Security Essentials (MSE) with the latest signatures. To do this, simply launch MSE, go to the update tab and click the Update button, and then reinstall Google Chrome. We apologize for the inconvenience this may have caused our customers."
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