At the end of February, Microsoft sued personal navigation device maker TomTom for violations of eight of Microsoft's patents, three of which deal with file system and memory management issues within the Linux operating system of TomTom devices.

The Dutch company responded this week by countersuing Microsoft in the Virginia District Court for violating three TomTom patents. The countersuit seeks not only damages, but entreats the court to block Microsoft's legal actions.

Microsoft initially wanted to establish a licensing agreement with TomTom, and sought an injunction only as a last resort. Microsoft's Corporate Vice President and Deputy General Counsel of Intellectual Property and Licensing, Horacio Gutierrez said in a statement yesterday, "We are reviewing TomTom's filing, which we have just received. As has been the case for more than a year, we remain committed to a licensing solution, although we will continue to press ahead with the complaints we initiated in the US District Court for the Western District of Washington and the International Trade Commission."

But due to TomTom's position as a Linux implementer, and Microsoft's prior claims that most free and open source software (FOSS) is built upon a foundation of 235 different Microsoft patents, many see this patent battle as a part of a larger-scale crackdown on Linux by the Redmond company.

At the time of Microsoft's filing, Jim Zemlin of the Linux Foundation said, "Right now the Microsoft claim against TomTom is a private dispute between those two entities concerning GPS mapping software. We do not feel assumptions should be made about the scope or facts of this case and its inclusion, if any, of Linux-related technology."

Attorney Andrew Updegrove of tech law firm Gesmer Updegrove believes the move signifies an internal division within Microsoft on its support of open source software: "The schizophrenic strategy that the proprietary 'old guard' of Microsoft continues to push -- seeking to threaten Linux in particular and open source in general, while simultaneously claiming to support this new model to its customers -- will ultimately collapse."