Sorry for the late reply.
Yes, the balance actually shows BTC0.00 now + unconfirmed BTC2.71
As for the payments tab.
The last transactions are from 23 Nov and prior to that 9th Sept.
The transaction overview says Status: Unknown transaction status.
Can you post the tx id of the last transaction? To get it simply go to the transaction overview and click next twice. It's under transaction detail.
You've either got your money stolen or have encountered a bug. If it's the latter then I'd try reinstalling multibit (back up the seed) and/or create a new wallet and transfer all the funds to that wallet. If none of that works then use another client.