IE back button not working for my web site

IE back button not working for my web site
Hi all,

I am fairly new to web-development. While developing an internal web-site i created two pages with menu, one of them is parent menu page (left menu) which nevigates to the another page with tree menu.

Problem is that I couldn't show the page with tree menu as part of the master frame i.e where the other pages normaly appear, so I set the target = _top. This means that the page with tree menu actually takes place of the parent page. Now when I click back it doesn't go to the parent page but stay on the same page. I guess it has somthing to do with the target = "_top" thing but I cant remove it as explained above.
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