Checkbox Disable Field Browser Back

I have a form with some text fields that are disabled UNLESS a checkbox is checked. Initially the text fields are disabled and the checkbox is unchecked.

The code is something like this:

Code:
function disableTextbox() {
if (chk.checked) {
txt.disabled = false;
} else {
txt.disabled = true;
}
}

<form action=something.cfm>
<input type=checkbox name=chk onclick=disableTextbox();>
<input type=text name=txt disabled>
<input type=submit>
</form>
When the form is submitted, some validation is performed. If anything fails, I display an error message and show a link to go back (history.back).

The problem that I am having is that when you click on the link to go back, the checkbox on the form is checked, but the text fields are disabled.

You have to re-click the checkbox to update the text field.