Since the system runs fine without SBC installed, then most likely it is a software problem, not a PC problem. There are other free firewall and anti-virus programs available through microsoft, and a host of other vendors, some good some not so good. I use a free (and ad-free) firewall, but I pay for anti-virus. You get get what you pay for, so be careful which product you choose. Most free software will want to bombard you with ads, or install some sort of tracking / monitoring software so they can sell your info to advertisers.