I'm in France so am with Wanadoo (Orange) with a ADSL broadband connection. I've got a Sagem modem (USB). I use AVG free for virus and Zonealarm.
I've used the above for years without any problem so can't think they are at fault.
I remember my problems started when I downloaded the new MSN, didn't like it for the "stopped" reason so tried system restore but that went haywire so I tried other messenger programs which were not as good so I downloaded MSN again and it seems to have settled down now. But left me with this "stopped" biz.
I had the same problem a couple of weeks ago . It was Zonealarm , i ditched Zonealarm and went with Comodo i have had no problems since .Do a search in Google and you will find loads of answers all pointing to your firewall.