weird browser crash with viewstates

[mark]

hard to explain this but ill try

basically ive two buttons that are disabled and are only enabled when
certain criteria is met
i have 2 drop downs and 1 text box - once data has been entered (set to
autopostback) - a var is set to true
and once all three are true - the buttons are enabled - this works kind of.

(code for dropdown changed etc is like this :-)
Private Sub dropdown1_SelectedIndexChanged(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles dropdown1.SelectedIndexChanged
ViewState.Add("one", True)
If ViewState.Item("one") = True And ViewState.Item("two") = True And
ViewState.Item("three") = True Then
Button6.Enabled = True : Button7.Enabled = True
End If
End Sub

text is the same just its a text box - the variables are declared on page
load

now the page is set in frames - top frame, left frame, mainframe - with
navigation buttons in the top and left
now if the condition is met that the buttons are enabled after entering the
data and you DONT save and click another
navigation button - then go back to the page with the disabled buttons - it
works well - however - you attempt to enable the buttons by reentering
data - the browser kindve crashes - everybutton / link is disabled on the
top frame and left frame - and the default main page is nulled (no page) and
nothing works - you have to shutdown the browser

any ideas ? if this makes sense!

mark