Kaspersky AV update troubles Microsoft users

Kaspersky Labs and Microsoft have recovered from an error that caused significant email troubles for some users of Microsoft's Antigen email security software.

Antigen users started receiving updates for their Kaspersky Labs antivirus engine again on Tuesday. Kaspersky and Microsoft had put those on hold after a flawed update caused trouble last week, representatives for the two companies said on Tuesday.

Steve Orenberg, president of Kaspersky's North American operations, said: "As far as both parties are concerned, the problems have been addressed and its business as usual."

The problems left some people without fully functional email systems for as long as 10 hours. The culprit was a routine update to the Kaspersky antivirus engine, which was distributed early on Thursday morning. Microsoft in the afternoon offered the previous version of the engine for download to solve the problem.

The Microsoft representative said in a statement: "As soon as we were aware that our customers were experiencing email problems due to the Kaspersky update, we escalated through the appropriate channels across Kaspersky and Microsoft, and were able to define, test and provide a resolution."

Antigen, which Microsoft acquired when it bought Sybari, uses multiple antivirus engines. The product is used by about 10,000 organisations, a "small percentage" of which use the Kaspersky engine, the Microsoft representative said.

While halting the updates for the Kaspersky engine for several days meant that one engine wasn't updated, users were still protected by the other engines and updates. Antigen can scan email with up to five engines at the same time, according to the Microsoft website.

Microsoft recently announced a new beta test version of Antigen.

Joris Evers writes for CNET News.com