I am not sure if it's just coincidence or what but after I installed NIS for a couple of days, the Win 7 started to check (chkdsk) my drive D for problems and it always tried to make corrections on the MFT (however, unsuccessfully because of "insufficient space" but actually i have tens of gigabytes available on my hard drive).
So I was wondering if anybody experienced the same or it's just me? any comment will be appreciated.