form onblur event

I am placing all my edits for a form on each form field onBlur() event. I usually use the onSubmit event, but I can't use the onSubmit event in this situation.

I only have a problem when there are 2 form fields with onBlur events in sequence.
When you leave the focus for the first entry - social -the alert box for the next entry co-social displays also. You then have to go to the task manager to delete the session. The following is the code for 2 form fields with onBlur events in sequence:

<td colspan="2"><font face="Arial, Helvetica, sans-serif" size="3">
<input type="TEXT" value="" size="20" maxlength="11" name="social" onKeypress="if (event.keyCode < 48 && event.keyCode != 45 || event.keyCode > 57 ) event.returnValue = false;" onBlur = "if (!document.loanapp2.social.value){alert('Borrower Social security number is a required entry!');document.loanapp2.social.focus();return false;};">
</font></td>
<td width="37%"><font face="Arial, Helvetica, sans-serif" size="3">
<input type="TEXT" value="" size="20" maxlength="11" name="co_social" onKeypress="if (event.keyCode < 48 && event.keyCode != 45 || event.keyCode > 57 ) event.returnValue = false;" onBlur="if(document.loanapp2.co_lastname.value != '' && document.loanapp2.co_social.value == ''){alert('Co-borrower Social Security Number must be entered if Co-borrower name is entered!');document.loanapp2.co_social.focus();return false;};" >
</font></td>