Here is link for the drivers you need if your modemhas a sticker on it that says "new" on it download the CM8738 file as those driver did not come on most disc.I just had the same problem with a system I put together for a friend.Also like glc stated this is not the best modem but it works.This one still will connect as good as my Diamond modem on my ISP.Hope this helps!!
http://www.pcwave.com/support.html