airport express service dropout

I recently bought an Airport Express to extend our wireless network and listen to music wirelessly. It worked perfectly for the first week or two but over the past week I've noticed that it'll just drop out at seemingly random times. What happens is that the front light will be flashing amber and when I open the Airport Utility the base station will be grayed out with the message "Such-and-such base station used to be part of your wireless network . . . " and rather than a button that reads "Edit" there will be a button that reads "Forget".

If I unplug it and then plug it back in it'll come back, but obviously this is a bit of a pain and I'd prefer for it to just work.

Any wisdom out there to offer?

Thank you.