Ever since I updated to iOS 5.1 I've had some new voicemails that I was unable to play without rebooting my iPhone 4S. I will see the new voicemail in my visual voicemail but it will show 0:00 and not let me play the message. When I reboot, it will notify me of a new voicemail and I'm able to listen. This has happened 4-5 times. It also happened today on my wife's 4S so it's not just exclusive to my phone. I am on the Sprint network. I tried searching the forums but didn't find any posts with a similar issue. Any ideas of how to resolve this? Thank you!