A class action lawsuit filed in Illinois last week alleges that Microsoft did not do enough to ensure that its Windows 10 operating system wouldn't cause problems for users who downloaded it.

The suit, filed Thursday in the U.S. District Court for the Northern District of Illinois, names three plaintiffs and seeks more than $5 million in damages. It was filed on behalf of all Microsoft users in the U.S. who lost data or whose devices were damaged after installing Windows 10.

Released in July 2015, Windows 10 was offered as a free upgrade for one year to any Microsoft users running previous versions of the company's operating system. While Microsoft touted the cloud-focused Windows 10, now installed on more than 400 million devices, as its most advanced and secure OS to date, many customers have complained about the company's aggressive efforts to get people to upgrade.

Prompts and Upgrade Hard To Dismiss

In the lawsuit, filed by the Chicago law firm of Edelman, Combs, Latturner & Goodwin, plaintiffs Stephanie Watson, Robert Saiger, and Howard Goldberg allege that Windows 10 caused their computers to lose data and stop functioning properly. While Saiger and Goldberg said they voluntarily installed the new OS, Watson claimed her computer was upgraded to Windows 10 without her permission.

All three plaintiffs said they lost time and money trying to recover lost data and resolve other problems caused by the upgrade. Watson said she eventually bought a new computer because her old one could not be successfully repaired.

The lawsuit also noted that Microsoft's prompts and upgrade offers for Windows 10 were difficult to dismiss and remove, and the operating system itself was not easy to uninstall if users found the upgrade caused problems.

"A great number of people have installed the Windows 10 system inadvertently or without full realization of the extent of the download," the complaint stated. "Once downloaded, the Windows 10 system does not have an option for its deletion. The program can be deleted but it takes a significant effort to find out how to do so; a typical user will not have the expertise to remove the system without professional IT help."

Next Update Promises 'More Choice and Control'

"The Windows 10 free upgrade program was a choice designed to help people take advantage of the most secure, and most productive Windows. Customers had the option not to upgrade to Windows 10," a Microsoft spokesperson told Courthouse News Service. "If a customer who upgraded during the one year program needed help with the upgrade experience, we had numerous options including free customer support and 31 days to roll back to their old operating system. We believe the plaintiffs' claims are without merit."

Numerous Windows users complained about compatibility and reliability problems after upgrading to Windows 10, and since then Microsoft appears to have adopted a somewhat less aggressive push with subsequent upgrades. For instance, it phased in last year's Anniversary Update over a period of three months.

Microsoft has since noted it plans to provide users with "more choice and control" when it rolls out its next big Windows 10 upgrade, the Creators Update, sometime this spring.

"Since we released the first version of Windows 10 we've received a lot of great feedback from customers about the way we deliver and install updates," Windows and Devices Group vice president Michael Fortin wrote in a blog post early this month. He said that the Creators Update will give users "considerably more flexibility when specifying the best time to install updates on your devices."