Radio Cuts Out

I have a 2004 Chevrolet Tahoe with the Bose stereo system. While listening to the radio ever few minutes and with no regular pattern the sound will cut out for just a second and then play just fine for a while then it happens again. No other symptoms. Any ideas?

I have a similar problem on my '98 Tahoe only sometimes it goes out for days. Mine doesn't seem to be affected by bumps at all. I would love to know the cause.