My Mac Pro is exhibiting odd symptoms: when I attempt to download a program or software update (from Apple), not docs, PDFs, or other items, my download speed ramps up to 175 kbs, then promptly decreases speed until it stops altogether. I have tried both ethernet ports, changing my IP address, etc., but nothing works. I have even tried downloading programs in Boot Camp with XP and had success. Is there a setting that I'm missing? Some security issue dealing program downloads?