The Windows 10 October 2018 update - launched this week - is reportedly deleting users' personal files after it is installed.
Microsoft has also reportedly taken down the update from its download site, and the company is not pushing the update to users via automatic updates.
"We have paused the rollout of the Windows 10 October 2018 Update (version 1809) for all users as we investigate isolated reports of users missing some files after updating," said Microsoft.
Users who are not concerned by the potential threat can still download the update for testing purposes.