IE 5.X - Back button option sometimes not available

[Kimber]

While browsing w/MS IE 5.X, eventually the back button becomes gray-shaded and not available. Clearing out cache and temp internet files doesn't help or fix. Problem occurs mostly when viewing threaded linked messages. After viewing about 3-4 messages deep, I no long have the option to go back.<br>
<br>
Is there some preference setting that needs to be adjusted?<br>

 

[KneeBreaker]

This happens to me, but it is when a new window is opened, and so you end up with multiple copies of IE running.