Interesting, out of stack space

[Jop]

I found something interesting (well, for me)

Private Sub Check1_Click()
Dim ha As Boolean
ha = Check1.Value
Check1.Value = 1
Check1.Value = Not (Int(ha)) 'This generates an error after a few seconds (Out of stack space), I know what the error means, but why is it happening here?
End Sub

Please note that I don't need the code (ofcourse there are better ways ), I was just testing stuff, nothing important.