I haven't used modem for a long time, but the things you can check : your NIC settings - you said you've already done that, try refreshing the DNS settings, try ping, traceroute, run "ipconfig /all" and see what it reports. Try calling the help desk, they may help with useful advice, as a last resort, try rebooting the PC, make sure to disable firewalls and anti-virus programs , just to rule them out.