Windows 7 was released in October

Windows 7 was released in October

The firm said it was looking into reports that suggest its latest security update, released on Tuesday 25 November, cause the problem.

Reports suggest the problem also affects Vista, XP and other systems. Software firm Prevx, which has issued a fix for the problem, says “millions” of people may be affected.

“Users have resorted to reloading Windows as a last ditch effort to fix the problem,” the firm’s David Kennerley wrote in a blog post.

“We hope we can help a good many of you avoid the need to reload.”