Arduino disconnects from PC when I plug in Protoshield.

I have a Freetronics Eleven (Arduino Uno compatible) board and I have made an 8 led flasher circuit on a protoshield, However, when the protoshield is connected to the Freetronics Eleven board and I plug it into my computer, the board disconnects. Does anybody know why or how to fix this problem?

drawing too much current from the USB port?

JKMotum:
I have a Freetronics Eleven (Arduino Uno compatible) board and I have made an 8 led flasher circuit on a protoshield, However, when the protoshield is connected to the Freetronics Eleven board and I plug it into my computer, the board disconnects. Does anybody know why or how to fix this problem?

Can you show us the wiring on your protoshield either via a schematic or neat drawing?