NU 16 speed disk used to work like a champ. It would defrag 80 GBs in less than 30 minutes. I don't know if a recent Windows Update (including MS Office 2010) has anything to do with it, but now it will run for a few minutes and then it hangs. The percent indicator doesn't change and my HDD light stays on. I have to click on the red stop button, but then it takes several minutes before it tells me if I want to abort. After I click yes, it takes several more minutes before it tells me that the process was aborted by the user. I've uninstalled, then reinstalled NU16, but that didn't solve the problem.