Mac dont boot with mouse or keyboard conected.

When i power on the mac with the mouse and keyboard coencted to USB the MAC don´t start and tell me a setup USB error. If i disconect the USB mouse and keyboard the computer boot fine, but if i conect the USB mouse or keyboard the computer give me a screen with "you have to restart the computer", restart and don´t boot again.-...please help!!! i thought this was caused by damage on the logic board, so i buy one on ebay, replace it and the same problem again. Maybe it is somewthing with software or OS, but i can´t do anything without a mouse or keyboard!!!! please help me!!! don´t know what to do