'We had a new kind of 'virus' attack today that people were calling in about,' said Mike Williams, a support manager with Clearwater, Fla.-based Sunbelt Software.

Mitch Wagner: Google's Pac-Man gobbled $120 million in productivity Other users spooked by the background sounds wondered whether they had been nailed by malware. Several Firefox users reported that they were able to eliminate the background sounds by disabling or removing the CoolPreviews add-on, which lets users preview links and media content without abandoning the active page. 'We just got DDOSed by Pac-Man,' Socal said another Mozilla engineer quipped, referring to a distributed denial-of-service attack, the malicious assaults that attempt to bring down a Web site. 'The pounding we took on the forums also caused replication on our slave databases to fall behind by as much as 1.25 hours, so even when we wrote an article about the noises, it didn't show up for most people,' Socal added. So many, in fact, heard the sounds that when they didn't find an explanation on Mozilla's support site, they posted enough questions on the support forum to slow the company's database server to a crawl.

'Even if Google was open in a background tab or window, or in a hidden iframe created by an add-on, the Pac Man music and sound effects would start. 'Unfortunately, in the initial release, sounds started playing automatically - an oversight or an homage to, I guess,' said Socol on his blog today. But the game freaked out some Firefox users, said James Socol, a Web development engineer at Mozilla.

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