The Massachusetts attorney general's office is investigating whether Microsoft tried to squash Linux in violation of the consent decree settling the company's landmark antitrust case.

Massachusetts, the only state still pursuing antitrust charges against the software maker, said in a court filing that it "is looking at several issues related to potential enforcement of the decree." These include whether Microsoft has retaliated against an unspecified computer maker for promoting Linux and has signed unlawfully restrictive agreements with Internet service providers.

A Microsoft representative denied the allegations. "Microsoft's compliance is being closely monitored, and the consent decree is being closely enforced," spokesman Jim Desler said on Monday.

"It's a curious filing, considering that there are several layers of enforcement over Microsoft's implementation of the consent decree," Desler said. "You have strict internal enforcement. You have Microsoft board enforcement as well. Externally you have the Department of Justice and the settling states. And you have the court."