LM7805CV output voltage drop to 2.5v after connecting load
Your input voltage to the regulator is way too high. You are generating V*I Watts in the regulator which is 30*your load current. These parts have a thermal protection circuit which will shut them down to protect themselves. You will probably find the part is getting hot.

You should be aiming for a voltage input to the regulator in the 10V region. To limit the power dissipation in the regulator aim for the lower end of the input voltage range rather than the higher.

If your thermal management is good it could be a stability problem  consider increasing C3 to 10n and make sure it is right across the regulator output also add another small capacitor (30n) straight across the regulator input. .     

If you really need to create 5V from such a high input voltage consider using a Buck switching regulator.