I have a graduate degree in telecom engineering and have been coding for 44 years, so I am pretty methodical in my trouble shooting. I have an Apple TV 1, ATV 2 and three Macs (Mac Pro, Mac Mini, and Macbook Pro). All are exhibiting this issue, both over a direct ethernet connection, and over WiFI. This occurs whether I use Verizon FIOS as my internet Service provider, or Clear. I have installed and reinstalled all relevant software. I also have Leopard, Snow Leopard, and Lion installed (on different machines) and all have this issue So it's not a wireless issue, and not a Provider issue. I have the problem on 5 separate devices, both dedicated (ATV) and ancillary (i.e., iTunes on a Mac computer). It is not system wide, as I too can get certain categories of stations (such as the bad 70s Retro I am listening to now). A prime example is the Eclectic category, which is entirely nonfunctional as a category, and my favorite iTunes/ATV internet radio station KCRW 24 Eclectic (Awesome station!) is in my favorites list and will not work. Surprisingly, I can go to KCRW Eclectic 24 through their web based program and access it fine - it is just through iTunes and ATV, which both use the same engine, that I am unable to access it. All other streaming services of all types, from Netflix to Spotify to Hulu to Pandora work fine.
So Issue is
Not Ethernet v WiFi issue (Connection Type)
Not Provider related (Verizon FIOS v Clear)
Not Equipment Kind Issue (ATV v access by Mac Computer)
Not OS related (Leopard v Snow Leopard v Lion)
Not Streaming Issue (Other Streaming services all Fine)
Is iTunes Related (Some Stations work, others do not & most damning, KCRW Eclectic 24 accessible through Web based channels, but not through ATV or iTunes, which use the same Apple code)
My conclusion is this is and Apple Issue, at the head end, in the code that drives radio station access in iTunes, and I certainly hope Apple is monitoring this and will do something about it!