iCloud keeps logging me out
I logged into iCloud this evening to check my email on my Mac. Thirty seconds later it logged me out. I logged in again, same thing happened. Then I logged in and tried to check a document in Numbers and and it closed the document after 15 seconds. Now it's just opening up new windows every 20 seconds or so, but leaving me logged in. Any ideas?
MacBook Pro (13-inch Early 2011), Mac OS X (10.7.5)