IP restrictions can be caused by a million things. Do you share your external IP with a large network (ie: school campus)? That is a possible cause, among many others.
Regardless, the restriction will go away in time and there's not much we can do for you here. Only real way around it is to lease a new IP, which in most cases for home users is just a matter of changing the MAC address of your router's WAN port (or your computer's MAC if you connect directly to a cable/xdsl modem).
Your sound card works perfectly.