when i was using the window 10 preview version then some window update came and when i started my laptop. it did not start. and i formatted my laptop and try window 7 , 8 and 8.1 initially it take to much time to start. now i am using window 8.1 initially in booting (blue screen) circle rotates very very slowly but when we press F2+F10 (go bios and save) or alt+ctrl+det (restart) then circles rotate normally. this problem is too much annoying me please help me.
