Page unload event question

 Hi All,
I have a series of content pages (which all use the same master page)
On the page_unload event, I am saving data to the current content page (before it navigates to the next content page)
The issue I have, is that the page_unload event fires when
a) I am loading the content page
b) when I fire a textbox OnChanged event (the textbox is in an ajax update panel)
 
I suspect that the page life cycle is causing the page_unload to be fired in situations 'a' and 'b'.
If I am correct about this, is there any way to prevent the content pages unload event from firing with the exception of when the page is actually being navigated away from (ie unloaded)
 
any innsights would be greatly appreciated.
 
Thanks!
Gord
 
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