I had a similar problem that arose a week or so ago with my Tuner. The lights alternated between flashing (at various rates), going dim, and not going on at all. It became very frustrating -- but long story short, it was eventually hooked up to a new power supply and, as of today, it works fine. Early on in the ordeal a Radio Shack employee tested the original power supply and suggested that it was fine and the problem was definitely in the Slingbox itself, but that was apparently incorrect. So, try a new power supply. It seems to have worked for me, and your problem sounds similar to mine.