A judge has tossed out a case against Microsoft by Novell who claimed that the software giant's anti-trust antics stuffed up the success of WordPerfect. The ruling ends the last private antitrust action against the world's largest software maker, at least in the US.

In his judgement, US District Judge Frederick Motz said that since Novell transferred its claims related to its PC operating-system products to Caldera in a 1996 purchase agreement, it couldn't pursue the lawsuit.

Motz has apparently decided that allowing Novell to continue the two antitrust claims was in error. He said that Novell's primary contention is that all the asset purchase agreement meant to assign was claims for harm inflicted" on Novell's PC operating system.

Novell briefly owned WordPerfect in the mid-1990s and claimed that Microsoft's anticompetitive tactics undermined the product. WordPerfect's share of the word-processing market fell to less than 10 percent in 1996 from almost half in 1990.