How big's the pot? How old's the plant? Has it got roots coming out all over the place or just one spot? If you're watering often enough they won't grow roots out of the pot searching for more water.
Pot that size (depending on plant size and stage of growth) should be watered every 3 days or so if in soil.....go by the weight of the pot when it is dry rather than a set time to water. Like stumps said...they are looking for air....either that or a way to commit suicide to avoid the slow drowning. Roots coming out of the pots are fine.....your watering frequency is not....slow it down and all will be fine.