Latest week, I've bought a new motherboard and a DDR3 Ram, as my older MB was DDR2. But my computer started acting weird, so I formatted my HD and installed Windows 7 again. When I tried to open Windows Update, Explorer.exe suddenly crashed and I had to restart it. Then I checked for updates. It took a while and it found them. When it was done downloading, the installation began. After some time, an error happened and no updates were installed. I tried again and the same thing happened. I restarted the PC and tried again, and some updates were installed this time, but the error came back. I restarted my PC, as some of the were installed. But another error happened and the installation couldn't be finished. This Monday, I changed my MB again. But the error persisted. The next day, I bought a new HD, as my old one was 4 years old, so I thought it was failing and it was the cause of all those errors. But the error still happened. I've already checked for memory errors using memtest. And sfc /scannow never finishes. I honestly don't know what could be the cause of this. Thank you for your patience.