WD TV & WD TV Live Cant Fast Forward or Resume .mkv movies anymore

not sure what the heck is going on i have both players using a 1 TB maxtor ext drive i have always been able to fast forward and skip chapters on .mkv movies. the drive went bad so i grabbed a 2 TB seagate. when i try to fast forward i get an error message about “trick something” or after getting the lastest firmware on the live it says “unable to play file”