This was a frustration with OOTP9 and still hasn't been fixed. I'll just provide a link to last year's thread.
http://www.ootpdevelopments.com/boar...7-odd-bug.html
This is the post that explains it best.
I just had this problem with the backspace key not responding until I went to a menu and then it immediately went back to the previous page.
I think I know what's happening. I noticed that the focus got moved (not by me!) to the search bar up top so the backspace key does nothing while in that bar. To test this the next time it happens to you, start typing some letters in and see if they appear in the search bar.
It's a similar issue as some web pages have. You hit the backspace key expecting to go back a page and instead find it doesn't work because of a flashing cursor in some text box somewhere which makes the backspace key do nothing but erase, but of course, there's nothing to erase so nothing at all happens.
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