Faulty signature updates resulted in Microsoft's Live OneCare anti-virus service falsely reporting Gmail's website was infected with a computer virus.

The false alert, which arose for a signature update issued late last week, meant OneCare users visiting Gmail were warned that the site was contaminated by a virus called BAT/BWG-A, News.com reports.

Microsoft rectified the SNAFU with a revised signature update late on Sunday, but not before the issue had hit a significant number of users, as posts to OneCare and Gmail forums (here and here) show. The glitch often hits OneCare users updating to IE7, Virus Bulletin notes.

The software giant has apologised for the false positive alert on the popular webmail service, which it attributes to mistakes in understanding coding changes made to Gmail last week. The software giant is reviewing its procedures to prevent a repetition of the problem.

False positives among anti-virus packages is a problem by no means confined to Microsoft's fledgling OneCare service. In March, a faulty signature update from McAfee's falsely identified components of MS Office as a low-risk virus. In another similar incident, MS anti-spyware labeled security software from rival Symantec as a Trojan back in February. ®

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