regular circuit breaker doesn't trip.....when changed out to ground fault breaker it trips
GFCI breakers trip if either: 


there is an overload
there is a ground fault 


Regular breakers trip if: 


there is an overload


From here we have a simple high school logic question.   If a regular breaker does not trip, and a GFCI breaker does trip, what kind of fault condition are we talking about?   

Right first time :) 

So now you need to find and kill that ground fault before it finds and kills you.