Failure to connect fully to internet after shutting down?

Dell desktop running XP will not connect to browser after switching off until it has been re-booted many (up to 10) times. Overcome on a regular basis by closing down to hibernate, but the need to close compeltely after new programs or updates results in the fault condition. The connection is made from the wired in router and shows full activity with packets sent but only 10 - 20 or so packets received until it finaly catches and packets received number rises into the hundreds. Can anyone suggest where the fault lies and how to overcome?