Question : network bandwidth

is there software that graphically shows who is using the most bandwidth on a network? I was told about things like IPTRAF and WIRESHARK, but I don't know enough about packet traffic to look at a list of IP addresses and bytes to know who is using the most bandwidth.

Answer : network bandwidth

Are you using any third party components?
Does the program work as intended despite the error message?
Try displaying the call stack. that may give you a bit more info:
http://msdn.microsoft.com/en-us/library/ms171366(v=VS.80).aspx