Your balance in the bank account was zeroed out as an expense account.
Here is what we did when an asset account was changed to an expense account and then we ran YE (we didn't know it had been changed):
 
I would make a copy of your company to test this in to see if it will fix your problem
 
Leave the account as an expense account (E) and do a journal entry dated in the past year (3/31/07) between the in error expense account (a credit) and an asset or liability account (debit), using what should be the YE balance as the amount.  Pick an account with very little or no activity so that the transaction is visible.  
Post the transaction.  
Change the account to an asset account, and do another JE between that account (debit) and whichever asset or liability account you used in the previous transaction, dated 3/31/07, and post.
 
Year end balances and retained earnings should be correct.
Hope this solves your problem.

I wish I could take credit for it , but it was my very smart accounting wizard, Donna that deserves the credit.  I'm glad it worked for you!