Dozens posted on social media that Windows Search stopped working for them, as of Wednesday morning.
Users say that when they use the desktop search tool it brings up a blank box rather than related results.
It is currently unclear how many of the operating system's 800 million users worldwide are affected by the problem.
The BBC has asked Microsoft for comment.
The tool is one of Windows' most used facilities, and normally makes it easy for users to find files, apps, emails and other content stored on their computer. However, users are now faced with a large grey box.
"The taskbar search doesn't work for me now, I have to scroll up and down the start menu like an animal," tweeted one frustrated user.
Another wrote: "I thought it was just me until I saw other people reporting the same thing within the past few hours".
Some users have reported that disabling Bing in the Windows 10 Start Menu resolves the issue.
It comes after the US National Security Agency (NSA) discovered a major flaw in Windows 10 which could have been used by hackers to create malicious software that looked legitimate.
Microsoft issued a patch to that bug and said it had seen no evidence of it being exploited by hackers.