OK, the final thing to check, HDD
www.hdtune.comsee whether your HDD drive status is OK...
Compare Current and Worst Values
normally, the values should be the same or have only slight differences such as 1~10
and you can also scan your HDD speed (Benchmark)
the average read speed should be
~30 MBps for 5400rpm drive
~60 MBps for 7200rpm drive
If your drive show any abnormal behaviour, there's no point formatting and reinstalling Windows