Behavior like that is typically the result or a failing hard drive, or faulty RAM. Download The Ultimate Boot CD and use the included hard drive diagnostic tools that match your hard drive manufacturer. Then go download a copy of MemTest86+. A copy of MemTest86+ is included on the UBCD, but it is an outdated version that may not work properly (produce inaccurate results) with the i7's memory controller and the ram you have installed.
Edit: Oh, and I found your other thread asking the same question with a different topic. It has been removed. Please do not double post.