I don't think there is any link between the router and the problem with the monitor. The symptoms you described appear to be a filter problem in the monitor's power supply. Have you switched monitors or tried this monitor on another PC (maybe a friends), if you don't have another PC, to be absolutely certain the monitor is the problem? You mentioned that the monitor is a Sony which came with your Dell. This could cause a problem obtaining parts because they may only be available from Dell rather than Sony. Can you supply a Sony Model number, somethimg like KV-xxxxx?