If ipconfig /renew returned the message that it was "unable to contact your DHCP server"it usually means that the computer requested an ip address properly but the modem did not respond. It is very possible the modem is damaged or needs to be reset to the factory defaults.

The possibility of system corruption should not be excluded though, however the chances are considerable that if the computer did not show any sign of spyware the issue is generated by a damaged modem.