Bad Microsoft patch trapped you in a boot loop? Here's your fix

Microsoft has thrown a life preserver to customers whose PCs were sunk by a recent botched security patch, in the form of a bootable recovery disk that can automatically uninstall the offending update.

Redmond first owned up to its error on April 12, when it admitted that some customers experienced problems after installing security update 2823324, part of Microsoft's April Patch Tuesday update bundle.

The fix was meant to address vulnerabilities found in a file system driver in Windows 7 and Windows Server 2008 R2. But some customers got a lot more than they'd bargained for, when after installing the update their machines failed to restart, applications failed to load, or they were treated to the notorious Blue Screen of Death.

Microsoft traced the problem to conflicts with certain third-party software – notably, some antivirus programs – but it advised all customers to uninstall the update and wait for a revised fix.

While that may have been sound advice, however, the various removal methods that Microsoft described all required customers to log into their PCs and follow a series of steps. But customers hardest hit by the glitch reportedly found their computers locked into a continuous boot loop that wouldn't even let them reach the desktop, let alone perform the complicated uninstall procedure.

On Thursday, the software giant offered a new solution: a bootable image that customers can use to create a rescue DVD or USB drive that can remove the bad security update automatically.

The image is supplied in ISO format, which is supported by a wide variety of CD-burning and file-management software, both commercial and open source. Windows 8 even includes ISO support baked into Windows Explorer.

The tool does have a few caveats, however. Microsoft says it will not run on older, pre-2004 hardware that doesn't support Never eXecute (NX) technology. It also only works on 32-bit Windows 7 installations – not on Windows Server 2008 R2, and not on 64-bit Windows 7 installations, which doubtless excludes many.

What's more, the recovery disk won't work on drives that have been encrypted using Bitlocker, because someone booting from a rescue disk and rummaging through the files on your drive is exactly the sort of thing Bitlocker is designed to prevent.

Finally, Redmond recommends you only use this tool if you absolutely have to. If you can boot your PC to the desktop and follow the instructions posted earlier, you should do that.

Affected customers can download the repair image from Microsoft's website, here. ®