Client Initialization Error

[pb0004]

I have AT&T U-Verse and on my TV, it says "Client Intialization Error" and has one option. "Quit Client" I clicked on that and now it won't load. When I try to go on the internet, my computer says "Unable to make a secure connection to the server. This may be a problem with the server, or it may be requiring a client authentication certificate that you don't have." My xbox can't connect to the internet either. Can someone help me or is the only way to call AT&T?