Parallel Networks has filed a lawsuit in the US over two patents, which it was granted the patents in 1999 and 2002, and which it alleges Microsoft is willfully infringing.
The patents cover systems and methods for managing dynamic web-page generation requests.
Other companies Parallel has sued for patent-infringement include Netflix, Amazon.com, Orbitz and Priceline.com.
The Texas court where the case is filed is historically sympathetic to plaintiffs in patent-infringement cases. A jury there last month ordered Microsoft to pay collaborative content specialist i4i US$200 million (NZ$305 million) in another patent-infringement case.