Mine also stopped working...has been working great since 5/08, the only issue I have had in the past was needing to be unplugged and replugged in after a power outage. Please note, this post is NOT related to a power outage.
I went to use it last night and got a message on my TV saying searching for signal...I thought that was odd since there is no way to turn the Roku box off. I tried unplugging and replugging similar to above, with no results. I see some people are saying it is the power supply, but I am skeptical of this. When I unplug the power, the TV says check signal cable (as it should) but when I plug the player in, the TV says searching for signals/no signal. (I am using HDMI cable) To me, that would mean that some amount of power is getting to the Roku Box, and therefore power supply/ac adapter does not seem to be the issue. Judging by the # of posts on this, could this perhaps be a "planned" End of Life for the unit?