actually, the cost index does not need to be limited to just 100, depending on airlines and schedules and delays etc..they will run different numbers..and so can I in the 757, so if that input other than 100 is crashing fsx, there is something wrong..i don't get that crash, nor any other kind of fms crash at all..just can't get manual control after A/P disconnection, sometimes for an entire minute, i clocked it. even the new fsuipc 4.5 did not help..that still remains.