BSOD

That is the Windows kernel and can be due to many things, which would take a lot of luck and effort to find. In the end a clean install is the best fix, although a repair installation can save a lot of time.

To do a repair install follow the guide here for REPAIR INSTALLATION. A repair installation will save your programs and files and just replace Windows, you just need to do the updates.

To save time on the updates, download the latest SP1 iso image of the same version that you are using from DIGITAL RIVER.
 
*sigh* A repair/reformat should be the LAST option.

First and foremost, download BlueScreenView and post the BSOD STOP code/Error message. Thats usually enough to narrow down which component the problem is.

In the short term, run memtest86+ for a few passes, and see if you get any failures.