Oh boy! It appears that Microsoft’s glowing track record with Windows 7 is about to come to an abrupt and unceremonious end. According to various Web sources, the RTM build 7600.16385 includes a potentially fatal bug that, once triggered, could bring down the entire OS in a matter of seconds.

The bug in question – a massive memory leak involving the chkdsk.exe utility – appears when you attempt to run the program against a secondary (i.e. not the boot partition) hard disk using the “/r” (read and verify all file data) parameter. The problem affects both 32-bit and 64-bit versions of Windows 7 and is classified as a “showstopper” in that it can cause the OS to crash (Blue Screen of Death) as it runs out of physical memory.

[ Read the Test Center review of Windows 7 RTM. Follow these seven steps to better Windows 7 security. ]

I tested for the bug against three different Windows 7 OS configurations on two different hardware platforms: an Intel Atom-based netbook running the 32-bit version, an Intel Core 2 Duo notebook running the 64-bit version, and a VMware Workstation 6.5.2 virtual machine running the 32-bit version.

In each case, the utility executed the first three stages of the test correctly using modest amounts of memory (several hundred megabytes). Then, when it entered the fourth stage (a read test), the chkdsk.exe utility’s memory consumption started to climb rapidly until several gigabytes had been allocated to its process and the test systems in question began to run out of memory.

Note: I did not succeed in causing the systems to “blue screen” as others have reported. However, I did observe chkdsk.exe consume up to 90 percent of the available physical memory on a 2GB VMware virtual machine. After that, the utility appeared to hang while all other operations in the OS slowed to a crawl for lack of RAM.

I also verified that the problem exists with the integrated disk check utility in Windows Explorer. When you use this function, explorer.exe starts consuming RAM like it's going out of style, pushing my test system to 98 percent memory utilization in just a few seconds. Worse still, explorer.exe failed to release the RAM when I canceled the disk check, and grew even more despite the fact that the check was now deliberately aborted. My only recourse was to either reboot the system or try to manually kill and restart explorer.exe.