grounding loop issue

Hi
I was rewiring my home made arduino to use a type B usb connector instead of type A as that's the usual standard. The entire circuit has many gnd wires , so to keep it tidy I decided I'll tie my usb connector directly to my dc jack. However the usb connection stopped working immediately. When soldered it to the gnd pin of the regulator it works. why?

You may have your DC jack wired incorrectly. From a typical DC wall wart style supply ground is RELATIVE. Tieing the USB VCC and GND with the DC side may make the boards power system to appear to be run from a negative supply. I've done this with serial connections several times. USB is no different.