Updated Microsoft’s fix for the Meltdown and Spectre bugs may be crocking AMD-powered PCs.

A lengthy thread on answers.microsoft.com records numerous instances in which Security Update for Windows KB4056892, Redmond’s Meltdown/Spectre patch, leaves some AMD-powered PCs with the Windows 7 or 10 startup logo and not much more.

Users report Athlon-powered machines in perfect working order before the patch just don’t work after it. The patch doesn’t create a recovery point, so rollback is little use and the machines emerge from a patch in a state from which rollback is sometimes not accessible. Some say that even re-installing Windows 10 doesn’t help matters. Others have been able to do so, only to have their machines quickly download and install the problematic patch all over again …

Those who have suffered from the putrid patch will therefore need to disable Windows Update as just about the first thing they do. Keeping the machine off networks seems a helpful precaution.

The Register cannot find a Microsoft response in the thread, a reasonable lack-of-reaction given many of the complaints accrued over the weekend.

AMD CPUs are immune to Meltdown but susceptible to Spectre, but the silver lining in that cloud has been dirtied by the patch problem. ®

Updated to add

AMD's been in touch to say it is "... aware of an issue with some older generation processors following installation of a Microsoft security update that was published over the weekend. AMD and Microsoft have been working on an update to resolve the issue and expect it to begin rolling out again for those impacted shortly."

Indeed, you may find a resolved Windows patch here for AMD machines.