Of the 20 products submitted for testing to independent security certification body Virus Bulletin, six generated false positives when scanning a set of known clean files.
As a result, the product failed to earn VB100 certification, a prized accolade in the anti-virus industry. The tests were the first carried out by Virus Bulletin on 64-bit Windows Vista anti-virus and anti-spyware packages.
John Hawes, technical consultant at Virus Bulletin, said: "The items added to our set of known clean files this month mostly consisted of common items taken from the 'most-popular' lists of free download sites, so it is a concern that the additions have caused such an upsurge in false detections.
"A false positive can cause as much disruption as a virus infection. False warnings often lead end-users to delete valid files in the belief that they are some form of attack and the resultant damage can be significant," he added.