You may be at risk if you're running Windows 8.1 on a Samsung computer. A bizarre bit of software, first spotted by Sysnative Forums staff members Richard Burgess and Brian Drab, blocks Windows updates from installing automatically, including security patches.

The bug doesn't kill Windows Update entirely. Instead, it simply switches from automatic downloads to manual controls. As a result, you're less likely to get these updates when you need them.

This kind of thing isn't unprecedented, but usually it's caused by malware rather than extra software added in by the computer manufacturer. However, Samsung claims it just wants to give people as much choice as possible.

"It is not true that we are blocking a Windows 8.1 operating system update on our computers," Samsung told BBC in a statement. "As part of our commitment to consumer satisfaction, we are providing our users with the option to choose if and when they want to update the Windows software on their products."

In another post, by Microsoft exec Patrick Barker, also a member of the Sysnative Forums, Barker notes that Samsung appears to have added this tweak after it already sold the devices, and without asking first. Even worse, it can't be uninstalled. In an official statement, Microsoft reiterated the importance of Windows Update and said it's already in contact with Samsung. Hopefully this can be sorted out quickly.

Update: In our original post we said the software was spotted by Microsoft's Patrick Barker. It was actually first noticed by Sysnative Forums staff members Brian Drab and "neimiro" (Richard Burgess) and covered subsequently by Patrick Barker.