Can you tell me a little more about your experience with your Vizio TV. Does Pandora launch and then closes out or does the app not launch at all?
In the meantime, let's try some troubleshooting. First make sure that your device has the latest firmware by checking for a new update. If an update is available, try loading Pandora again once the update is complete.
If you're still having the same problem, then please try a few standard network troubleshooting steps:
Try connecting directly via an Ethernet cable rather than using Wi-Fi (if you have this option on your device), and see if it works better.
Try rebooting your modem and router and then restarting the TV.
Remove and re-add the Pandora app from the device.