Have the same problem with a Belkin wireless router, but our phoneline has also been dodgy (which b.band feeds from) and we had dodgy cabling.
One way to save your legs if router is not next to pc may be to direct IE to the IP address of the router and reboot from there.
Otherwise check your wires for damage especially if they trail across doorways. Phone your ISP and/or phone company and get them to check. Ask about call out costs if they have to visit.