Calculating If's Balance equals then

I have two interest bearing bank accounts and a loan account.
Both of the bank accounts yield a higher interest rate than the interest due on the loan account.
As the account balances grow and the loan balance diminishes, I want to determine where the amounts meet to leave a balance of $10000 in the 7.5% account, $1000 in the 5.1% account and payoff the loan in full.
Unfortunately I keep getting a circular reference error because the balances include the withdrawals and it won't let me analyze the error. (I have Office 97)

Bnk1 -Int Rate: 5.1% Beg Bal $10000.00 Monthly Income: $190.44
Bnk2 -Int Rate: 7.5% Beg Bal $49073.80

Loan -Int Rate: 4.125% Cur Bal $107644.78 Monthly P&I Pmt: $1374.84

When I allow iterate, and maximum iterations 1, it changes all of the cells.
I am very confused as to how to correct this problem.
I'm totally unsure of what iterations does.
Can anyone help?
I have two spreadsheets, and the following columns in Each.

Spreadsheet One: (Loan ammortization)
Pmt Date | Beg Bal | P&I Amt | ExtrPmt | TotPmt | Princ | Int | End Bal |

Spreadsheet Two: Bank Account(s)
MM/YY | 7.5%AcctBal | Withdr | Int | 5.1%Bal | MoIncDEP | Int | Withdr |
I am attaching a zipped copy of the workbook, as well.