iBook loses cable connection

At times my iBook somehow gets knocked off line, in other words I lose the connection with my cable isp, usually after using iTunes through a firewire interface (a Motu 828 mkII), after unplugging the firewire cable. I haven't figured out the exact sequence of events that bring this on, but restarting the computer reconnects it and brings me back online.

Anyone know what could be causing the disconnect, or perhaps an easier way to reconnect besides restarting the computer?

Thanks,
Dave

iBook 600/10.3.3