Ajax not working in some computers?

there is a selection box when some one choose values from selection box next selection box will be filled according to value selected in first select box. Values are search from database . we using ajax here but it is working fine in 99 % computers and other 1% computers it show state 4 and also shows data in consol but this data in not coming response text after state 4 . Also when we run it locally it is working fine in every computer. Please help if you can.