Minimize the number of connections LW tries to use at startup

-clean out your incomplete folder (try to limit the number of incompletes downloads to about 4)

-set the options to manually connect on startup (give it a few minutes after startup to settle down before you use file->connect

--call Comcast and tell them your cablemodem is having trouble maintaining multiple connections (if you bought the modem/router, check the manufacturer's home pages for similar problems: sometimes a firmware upgrade/downgrade helps)