Well, I don't consider it a MAJOR MAJOR earth-shattering bug as it's a specific one but, even so, it does exist on both the machines I currently have Windows 7 on. I'll say they're both running a certain version of Windows 7 x64 and leave it at that. Now, about that bug... If you open an Admin Command Prompt, and issue the following command: chkdsk <driveletter>: /r it seems as if chkdsk just goes a bit bonkers in terms of memory usage but only on non-system drives - my system drive is C:, and the command works fine on it, but on non-system drives, internal, external, it doesn't matter, formatted with NTFS, it goes a bit insane. How insane? Well, here's what it looked like after just running the command for 30 seconds (then killing the process): So, it's worth checking out if you happen to be running a certain version of Windows 7 x64, at least. I do believe the issue exists in both x86 and x64 versions, but I can't verify that as I only use x64 versions. It doesn't affect the system drive, as noted, and it does not affect FAT/FAT32 drives either. But I tested it on my secondary partition as well as a 160GB NTFS-formatted external USB drive and it happens regardless, just not on the system partition C:. It occurs when chkdsk hits Stage 4 - that's when you'll really see the RAM usage skyrocket fast. If the process is allowed to continue, it will consume all the RAM you've got, and finally end with a BSOD because of RAM issues. So... just a heads up. This exists in the 16385 RTM build as well as the "patched" 16399 build patches (these will appear on Windows Update soon enough and they have a curious side effect of updating the build number for a variety of reasons and the associated files). A lot of folks are all over this currently and calling it a "showstopper" but I wouldn't classify it as such. Yes, it can bring down the system from operation, but in my experience showstoppers are bugs/glitches that have instant "triggers" that can be replicated and cause an instant BSOD - hence it "stops the show" pretty much in the blink of an eye. I'm old, sue me... we old folks prefer the old definitions of such events... Good luck, and be careful if you have some reason to run chkdsk on NTFS-formatted non-system drives with the /r option. Edit: Updated reports state that some users experience almost complete RAM usage but no BSODs - most of those who report BSODs are on machines with 4GB of RAM or less. Even so, watching chkdsk suck down 7GB of RAM on an 8GB machine is a bit disconcerting, and it could still cause further issues so... we'll see what happens. This may not be that important to a majority of folks, but for enthusiasts, and especially for technicians working on client or corporate machines (testing, of course) that may be required to use chkdsk on drives this could be a potential issue.