Same thing happened to me, and if you do a search on reddit about Coinbase you see people experiencing all kinds of weird issues. Frozen/ lost funds, verified accounts suddenly lost verification status, credit cards not working etc etc.
Coinbase owes me money from a sale of ETH that I did about 2 weeks ago. It was supposed to have been an instant cash credit (and had worked very well in the past), but while this particular sale was completed the money transfer never came through.
After I opened a support ticket and sent some emails, they initially entertained me with standard meaningless replies that they were "looking into it with the highest priority" but finally responded by locking me out of my account without giving a reason.
I can care less about the account - after this experience I'm not going to touch Coinbase with a 10 foot foot pole - I have plenty of other options. It's just that I've lost access to my transaction records. Now the only proof I have is from a mini screenshot of the "completed" sale and the Coinbase address that I sent ETH to from my Mist wallet.
I'm surprised a company with such bad rep managed to get so much VC funds and to recently get expanded licenses to operate in New York. What is everyone thinking? Why are there no widespread news reports on how this company is behaving with people's money?