I had similar problems at first and then the Slingbox stopped competely. I believe this was due to a combination of a software fault, corrected through an update, and the frequency of power outages we have had lately due to the bad weather.
All I can say is that by starting again and resetting everyingthing on site (you need to be on the local area networkk at home) it has solved the problem and we are now functioning normally. This includes the narrow screen.
Maybe someone else has experienced the same probelm and can offer a better solution remotely. Have you tried the telephone helpline number?