My central air unit is freezing up on the outside unit (you can see the ice covering the pipe that goes from the unit to the house and it is 80degrees outside. You can hear the unit running but no air is coming through the vents. I left it off all night and it is cooling fine today. Is this something serious that I need to have looked at or is it just something that happens sometimes and can I prevent it from happening again?

Get an HVAC guy to check it... you might have a low freon level causing it to run constantly and ice up because there is no off period.

A clogged air filter can cause that, or have the system pressures checked, could have a leak and be low on refrigerant. These are the two most likely.