NEVER- repeat- NEVER leave your cable modem on unless you are ACTIVELY internet surfing WITH a HARDWARE Firewall AND a really good software/anti-virus software like NORTON Internet Security with ACTIVE automatic anti-virus updates. Anything LESS these days and you are a total SITTING DUCK! Go to a hardware store and get a remote on-off switch (since many cable modems don't have them easily accessable) and FLIP YOUR CABLE MODEM OFF when not in use. This is why VIRUS writers and hackers are having a wonderful time- because so MANY people do not realize that THEY are using YOUR computer and IP connection!