Issue with ND, PFD and DU

Hello, two times today i've had this problem, while in the final approach, the screen of the PFD, ND and lower DU frezes... i continued my final descent but the screene remained the same.. if i clicked on them to popup i saw it moving while on approach (for example i saw the altitude go down) but in VC i saw the screenies frozen.. Why? Thank u..