dvd freezing

When viewing dvd's, some rentals some owned often have the picture freeze. this only happens once or twice during the whole movie and is usually short in duration 1-3 secs.
But it happens in almost every dvd. Is this a problem with the player or is it the disc.
Player is a toshiba sd-4800

thanks Ken

this is a common feature on almost all dvds. the slight pause is probably triggered by the dual layer format of the dvd. the pause happens during layer transition and lasts about 1-3 seconds. The only players that do not pause are players with a twin wave laser pickup like the dvd players made by pioneer.