I'm still thinking the problem is your power supply....
In the datasheets of the 7805 you see two capacitors which must be mounted as close as possible to the 7805,
*one capacitor of approx. 330nF between input and ground
*one capacitor of 100nF between output and ground.
These capacitors are to prvent the 7805 from oscillating. Are these present in your supply?
Good luck again :)

Henk