Yes, it is Windows 7. Once you install win7 it completely takes over all your hardware in your computer, not to mention your power supply and even the power stick that you computer plugs into. win7 also automatically converts all the drivers you downloaded to special windows 7 code so it can control your hardware.

There is no possible way that the random freezing and reboots could be caused by your drivers, or your hardware, it is definitely windows 7 fault.

Good luck.