An anti-waste activist who copied thousands of "worthless" Windows XP and 7 restore disks has been jailed for 15 months.
Eric Lundgren, a 33-year-old Californian, planned to sell the discs to computer repair shops for 25c each, but Microsoft - which makes the Windows software - said it was copyright infringement, and each disc robbed the company of $299.
According to Lundgren, the discs would only be sold to people who already had a valid Windows XP Pro licence. Restore discs are used to wipe computers clean and reinstall the Windows operating system.
Lundgren said many people would throw away computers that weren't working well, when all they needed was for the operating system to be reinstalled. His copies didn't come with licences, and wouldn't work without one.
Microsoft doesn't sell the discs, either giving them away free when people bought a computer with the operating system on it, or providing them as downloads.
Lundgren's argument was that providing the discs in repair stores was much easier for customers than having to ask Microsoft to send one out, or downloading Windows and burning it onto a disc.
A judge ruled the 28,000 discs were worth $700,000, and gave Lundgren a 15-month sentence and a $50,000 fine, despite the testimony of an expert witness who said the disks were worthless without a licence, which the customer would already have paid for.
"I don't think anybody in that courtroom understood what a restore disk was," Lundgren told the Washington Post, after losing an appeal against the sentence.
Microsoft said Lundgren "disguised" his restore disks as genuine Microsoft products, exposing buyers to viruses and malware.
"Unlike most e-recyclers, Mr Lundgren sought out counterfeit software which he disguised as legitimate and sold to other refurbishers," the company said in a statement.
"This counterfeit software exposes people who purchase recycled PCs to malware and other forms of cybercrime, which puts their security at risk and ultimately hurts the market for recycled products."
Lundgren in turn said Microsoft was upset he was helping people extend their life of their old computers, ruining their "profit model".
Windows XP came out in 2001, and still has around a 2 percent market share according to analysts. Microsoft no longer supports it, meaning there are no more security updates or fixes, pushing users to upgrade to Windows 10, but many old computers don't have the power to run newer operating systems.
Newer versions, such as Windows 10, don't require restore disks - the operating system can reinstall itself, and brand new installations can even be done from a flash drive.