Microsoft has pulled a Windows 11 update after users reported boot loops and startup failures.

The problem is the June non-security preview update, KB5039302, which has left some systems requiring recovery operations to get up and running after install.

According to a message in its Windows Release Health dashboard, Microsoft isn't sure what the problem is, only that it seems to be something to do with virtualization. "This issue is more likely to affect devices utilizing virtual machines tools and nested virtualization features, such as CloudPC, DevBox, Azure Virtual Desktop."