Microsoft is encouraging its customers to uninstall an update released on Patch Tuesday that is causing blue screen on death (BSOD) errors on users’ computers, according to security firm Sophos.

The MS14-045 patch fixed security problems with the Windows kernel, the central component of Microsoft’s operating systems, but in rare circumstances is said to force users to reboot their systems.

Paul Ducklin, head of technology in Asia Pacific at Sophos, said: "Apparently, the BSOD is caused by incorrect handling of the Windows font cache file – and because that happens during boot-up, you end up stuck in a reboot loop.

"The reason this problem didn’t show up in testing is because it only happens under rather specific circumstances."

He added that users need at least one OpenType Font installed in non-standard directories, and for that to be recorded in the registry with a non-contextual filename for the bug to affect them.

Microsoft said they were investigating behaviour associated with the update, but in the meantime advised users to uninstall the update by following instructions on its website. It is also looking into other font related issues.

The company has been contacted for further comment.