Hmmm...

Assuming you have a broadband link, have you checked your MTU setting? Many broadband carriers (DSL and cable modem) have some limitations here, and you can lose your connection / get "out of sync" easily. You might want to check out this page for information about MTU and other tuning tweaks.

A good way to test the theory is to connect to the internet and only do pings. Use the ping -f command to force non-fragmentation of the packet, and adjust the size of the ping. See if you can find a point that it breaks.

I have this problem with my DSL carrier, and find that I have to force my MTU relatively small. But, having done that, I do not have that problem any more.