This looks like a memory issue as JessicaD suggested. It is not likely related to Windows 7 install since you have done 2 fresh installs already. Rule out your boot drive by loading a fresh Windows 7 on a donor drive (non SSD) and see how it runs. If all is well than it is not your memory and some kind of file access read/write problem on your bus causing issues. Memtest is a free download, just google and create a bootable CD and run it. I once had two brand new sets of Dominator memory go bad and random BSODS were they way it happened. Memtest found both failures out and Corsair replaced them.