Microsoft has filed eight anti-piracy lawsuits in five US states against companies allegedly distributing counterfeit versions of its software.

The software giant identified the companies' alleged illegal activity through several channels, including the new Windows Genuine Advantage program as well as customers reporting suspected pirated Microsoft software, said its lead lawyer Mary Jo Schrade.

The Windows Genuine Advantage program, launched in July, requires customers to validate legitimate copies of Windows before they can use Microsoft's various software download services. The program immediately came under fire from customers for bugs that, among other things, enabled users to easily bypass the validation process or identify legitimate copies of software as pirated.

David Lazar, director for Genuine Windows at Microsoft, said Microsoft has addressed initial problems with the program's validation software and is continuing to address issues as they crop up.

Microsoft also has a "secret shopper" program in which it sends people out to purchase the company's software from various distributors around the country to ensure they are selling legitimate copies.

All of the companies named in Monday's suits had been notified that they were distributing copies of software that are counterfeit or infringe on copyrights or trademarks Microsoft owns, Schrade said. Microsoft typically sends a "cease and desist" letter to companies first and helps them understand what they are doing wrong and take steps to fix it, she said.

"We take the first approach of education and then enforcement is basically the last resort," she said. "If we can prove that [notifying the companies] hasn't worked, we will sue them."

Microsoft has sued thousands of companies and has a high success rate of eventually making sure the companies stop distributing pirated products. However, the number of suits has decreased in recent years as Microsoft has stepped up its efforts to identify those responsible for distributing counterfeit copies of its software.

Those named in the lawsuits are: BWT (doing business as Computer Max), Data Day USA,, Winvtech Solutions, Global Computing, Ion Technologies, Compustar and Chips & Techs.