It isn't often that attempting to diagnose a problem with my desktop computer leads me to what is potentially a serious problem in the datacenter. I recently moved to Windows 7 x64 as my primary desktop. I had been running the operating system on various machines since relatively early in the beta process, but migrating my main working computer to a new OS is always a chore I tend to put off for a bit.

But I finally bit the bullet, lined up Windows 7 and 64-bit versions of all of my key applications, and did a clean installation on a new hard drive. I've gradually been reinstalling my regularly used applications as I moved my workload on to the new OS, but about a week ago I started experiencing random freezes where I would lose access to the computer for anywhere from a few seconds to a few minutes, with the occasional reboot required.

The issue manifested in a really bad way when I tried to move data from multiple DVD drives to different hard drives. The system locked up hard and required rebooting each time I tried the same process. This was enough to motivate me to look for a fix to the problem.

I was open-minded about it; the computer is a couple years old and I was open to the possibility that I was having a hardware failure, not an OS failure, but as my warranty is still in effect I wasn't too concerned if that turned out to be the case (Dell support for their XPS systems has been pretty good in my experience).

But while searching for a possible root cause it turned out that there was a hotfix for the problem of random freezes, not just with Windows 7, but also Windows server 2008 R2. The hotfix was released on August 12th.

Microsoft describes the symptoms as:

A computer that is running Windows Server 2008 R2 or Windows 7 stops responding randomly. Applications or services that are running on the computer stop working correctly. Additionally, you cannot log on to the computer by using the remote desktop connection utility.

And the cause as:

This issue occurs because of a deadlock condition between the Lsass.exe process, the Redirected Drive Buffering Subsystem (Rdbss.sys) driver, and the Winsock kernel.

The hotfix is part of what will eventually (early 2011) be released as SP1 for Windows 7 and Windows Server 2008 R2.

Hard to think of a bigger nightmare for datacenter IT than an OS bug which causes a random server freeze, but if you are running Windows server 2008 R2 and have experienced this phenomenon, here's a possible fix for you. As for me; I've applied it, and the desktop hasn't locked up today.