My sister is having a hard time finding an error in her checking account. This was my reply; If anyone has their own tips and tricks for this, please comment.

Do you use Quicken? Try searching for a transaction amount that is half of the difference- Sometimes I enter things as income instead of expense.

Also, the transaction date could have been a typo; you could have entered a transaction that is not only in error but got a date in 1994 or something. Those will really screw you up; I have taken to posting a checkpoint transaction at the end of the month; A Misc. expense of zero that says instead of the payee, For example;

CHECKPOINT BALANCE 3/31/11 IS $1711.43 0.00 misc

… This is just an example. Any similarity to bank accounts living or dead is purely coincidental.