checkbox viewstate problem

[Obie]

I'm running a simple test where I have a checkbox whose autopostback =
true and enableviewstate = true. When I click the textbox, code is
fired that increments a counter variable and displays the result in a
textbox.

Everything works as it should when I load the page and check the
checkbox. If I click the back button on my browser, then the check
box is still checked (should be un-checked). Now, if I click the
checkbox control again (now it's unchecked), page_load is executed but
the code within the checkbox control's CheckedChanged handler isn't
executed.

Any explanations/workarounds would be appreciated.