WINDOWS 2000
INTERNET EXPLORER 6.0 and FIREFOX 1.0
LIMEWIRE 4.4.5
CABLEVISION OPTIMUM ONLINE

I connect to Lime Wire fine, and am able to search and download some files. But eventually, while downloading a file, i see the rate drop until it hits zero, and then the connection goes from "excellent" to "disconnected." My cable modem (3Com) still shows that I have connected status, but when i attempt to get on by either IE or Firefox, there is no connection. After I reboot my modem, I can connect again. This is not a problem when I surf the net otherwise, but the same problem occurs if I try to download through WinMX. I talked to Cablevision and was told the issue wasnt my modem, as it is working fine as far as they can see from their end.

Please help!!