Where is the CO2 leaking from? of you cant tell for sure get a spray bottle of soapy water and spray it on every potential gap on the regulator, adaptor, coupler, and tubing.
Are you still using the standard "D" coupler that came with the kegerator with adapters?
If not, what are you using for pin/ball lock connectors, barb fittings or screw fittings? I have barb connectors and had to use screwclamps to make sure there was no leaks on either ends of the tubing.
Good luck, let us know a little more info if this doesnt solve the problem