I have got a problem here

I have a list of criterians.........when i click that criteran i have a window with a option of add and delete a rule to this criteria.
When i try to delete one rule ,the rule gets deleted and then when i press back button on the criterian window window ................it goes to the previous window and try to delete again which gives an exception.

Now the problem is ...........................
when i press the back button i want my browser to go to the list of criterans instead of going to the delete page.the code we used for the back button is

<span class="task"><a href="#" onclick="window.history.back();return false;">Back</a></span>

In what way i can improve my code to solve my problem..