Once upon a time (well, in March), Microsoft rolled out a patch for PCs running its Windows 7operating system. The patch, however, was incompatible with PCs outfitted with Asus motherboards, causing those PCs to crash under certain conditions. The damage wasn't widespread because the patch was labeled "optional," which meant a relatively small number of people installed it. Both Microsoft and Asus were aware of the conflict, according to Forbes.

But on April 12, Microsoft changed the status of the patch "recommended," which meant that anyone with Automatic Updates enabled would receive the patch. The result? A lot more people with PCs featuring Asus motherboards discovered that their computers would freeze or refuse to boot.

In technical terms, the problem occurred because Asus enabled a setting called Secure Boot, which protects the PC against boot loader attacks that can compromise a system before the OS loads. But when Microsoft released its update, Windows 7 did not support Secure Boot, hence the conflict.

Even though updates of key products like Windows go through a testing period, they can still carry bugs that pop up once the final release is downloaded by sometimes millions of people. Such glitches not only frustrate users but call into question a company's ability to scrutinize software before it wreaks havoc.

Asus tried to ride to the rescue to correct the problem, offering a support page that told affected users how to resolve the crisis. Microsoft also published a support document that provided information and pointed users to Asus' support page.

On its support document, Microsoft took the opportunity to market Windows 10, telling people: "The Secure Boot feature is supported in Windows 10. To learn more about the security advantages of this feature and about the upgrade path from Windows 7 to Windows 10, go to the following Windows website: www.microsoft.com/windows."

Affected Windows 7 users who don't want to upgrade to Windows 10 should be able to fix the issue by following the steps on Asus' support page.

Neither Microsoft nor Asus immediately responded to CNET's request for comment.