I bought a new HDD for my computer 2 months ago because I thought it was the problem, but the freezes are back again. My new installed Windows 7 x64 worked flawlessly until 1 week ago. Since then my computer is freezing once an hour (or more) and sometimes, it freezes that bad that it "decides" to reboot / shut down. I have tried all solutions that I've found on the internet but only one seemed to work: defragmenting the C drive. This fixed my computer for like one day. I must metion that, before the freezes appear, there's a buzzing sound coming from my PC, like it's trying hard to read something from the HDD (just how it sounds when you insert a scratched CD in the DVD writer - for example). My system is as follows: Gigabyte GA-H55M-S2, Intel Core i5-760, 4.00GB RAM DDR3, ASUS EAH5770 cuCore 1GB DDR5 and the HDD is Toshiba 500GB SATA-III 7200RPM 32MB. My question is as follows: Do you think that this might be a Windows issue? Or is it a 100% hardware issue? Last 3 times I reinstalled Windows on the previous HDD, it worked okay for some months and then boom, the freezes were back again.