Well...every time you do a hard shutdown...you create circumstances where you need to run chkdsk /r on the next boot.
Chances are, every time you do a hard shutdown, you damage some Windows files.
7B STOP errors, see info at http://www.aumha.org/a/stop.htm
. Scroll down to 7B, left column.
The error you get...basically states that there is no bootable drive present.
Since you just did a clean install...I would suspect hard drive problems or file system problems.
I'd run the correct respective hard drive manufacturer's diagnostic (long test) on that drive before I tried anything else.