Trouble with DSL connection.

I'm currently trying to find a reasonable resolution to a network problem. This problem has plagued both my boss and myself. What will happen is that you can be browsing fine for a while and then the connection will just drop. What I've noticed is that when the connection drops I am unable to ping out. Speaking with the ISP helpdesk, I'm told you can't ping because that it is low priorty traffic, but they can't answer why I can ping when the connection is restored. We are being told that loss of connection is caused by us excedeeing our flow-cache and that purchasing a static IP address would fix this issue. I'm running through an actiontec 704wg modem/router combination. My boss is going through a zoom modem connected to a standard router. In my case, I've switched to static ip addressing and that has resolved my issues. As for my boss, he's connected his system directly to the modem, reset the winsock and ip via the netsh command. Even with the system being connected directly to the modem, he is being told that he has over 1000 connections open. He's gone through and used tcp/ip view and he doesn't see any stay connections on any ports. In the past I've been told that this has been caused by either donwloading files or web browsing. My boss has said that he will normally see this problem later in the evening around 8pm or so. The isp we use is Souris River telephone, at srt.com. To what I understand is that use NAT for the DHCP server. If anyone has any information regarding any fixes or ideas what can be done to resolve this problem would be greatly appricated.