Microsoft's rationale for changing the default recommendation of four Claria applications -- Dashbar, Gator, PrecisionTime, and Weatherscope -- saying that published criteria for defining spyware and adware required it to review how AntiSpyware treated the quartet.

"We decided that adjustments should be made to the classification of Claria software in order to be fair and consistent with how Windows AntiSpyware (Beta) handles similar software from other vendors," the letter continued.

Also late Friday, a Microsoft spokesperson acknowledged that after Microsoft acquired Giant Company Software, the developer of what became AntiSpyware, but before publishing its adware/spyware criteria, the Redmond, Wash.-based company "received lots of vendor disputes."

"A few of these came from Claria," the spokesperson said.

Some anti-spyware vendors have similar policies in place for settling disputes with adware vendors. Computer Associates, for instance, which markets Pest Patrol, used such a policy in late March to re-evaluate Claria's adware, and found it met its requirements for detection.

"After review, Microsoft found that Claria['s adware products] still needed to be detected, but decided to make changes in the recommendations made to the users. It did this to be fair, to treat Claria the same way it treated other software vendors," the spokesperson said.

Before March 1, Microsoft AntiSpyware recommended "Quarantine" for the four Claria adware programs, which essentially removed them from the PC. After March 1, Microsoft's software recommended "Ignore," which if followed by the user leaves the adware in place.