There were too many people(and some services) yesterday that was not updated. So chain of blocks belonged to old client become longer and had more chaintrust, than a newer one.
To prevent potential losses we decided to move back to old wallet for awhile.
Now we compiled new wallet and we will send alert which will forbid work of services and exchanges.
Regardless, that old wallet will accept new blocks(but new wallets wouldn't accept blocks generated by old wallets), it is strongly suggested to update your wallets. Otherwise you can loose your money, froze transactions and so on.