2001 Dodge Stratus • 4 cylinder Automatic • 123 miles

My dodge stratus 2001 is overheating recently. About a month ago it overheated for the first time and we realized it was completely out of coolant. We didn't find it odd seeing we hadn't replaced the coolant in years but in little less than a month it is completely out of coolant again and overheating once again. We have checked for leaks. The radiator also seems to not have any coolant in it at the moment so the coolant isn't circulating through the system. What is the problem?
April 20, 2011.

Check the thermostat and water pump

Apr 20, 2011.
Get the coolant system pressure tested to find the source of the leak, the coolant is going somewhere, If it is overheating and boiling the coolant out, check and test coolant fans, thermostat, and get a chemical test done to check for combustion gases in the coolant(head gasket/ head problem)

Apr 20, 2011.