I unlocked my phone using the "jailbreakme.com" by dialing on the emergency No. *#307#...

I was testing the wifi music store previews, and they play about 1/2 a second and then stops and say "unable to play preview"

It happened to both my iPhones + one guy in the net (i searched in google)...

1. What might be the problem?
2. And anyone else have this problem too?
3. And how can i fix it?

Guys, do you recommend restoring? or is it a fixable problem?