Go into the BIOS at startup by hitting probably f2, but may be different, look for a message that says hit XX to enter setup.
once in there either look for a setting that will "enable USB keyboard support".....if you can see that one then enable it.
if you can't see that setting look for one that says Halt on errors" which will probably be set to keyboard only... set it to none.
Save setting and exit and it should start up OK with the USB keyboard plugged in.