LOW IIS Web Connection Limit - Server Unresponsive

My website, which runs on IIS 6 via server 2003R2, seems to become unresponsive when its web connections go above 100.

I see this by using the performance monitor and running the Web Services\Current Connections (_Total) counter.

It also seems that the TCPv4 Connections established is approximately the same number as the web connections.

It is unusual that it can only handle 100 connections, given the fact that RAM and CPU usage remain low during times of web connection escalation.

Any ideas as to what I could try would be GREATLY appreciated!</div>