Like the title says, apparently my IE8 has stopped keeping the history of pages I've visited. I've searched SU and Google and can't find anything that seems to describe what I'm seeing. I have IE set to retain history for 999 days (the maximum allowed):
As you can see below, apart from today and last Thursday, IE appears to be oblivious to any activity more recent than three weeks ago. Clicking on either "Thursday" or "Today" reveals no recorded history, however. Very odd behavior. Finally, the history does extend back 30 weeks to when I built the computer, and there is recorded history for every week. I'd appreciate suggestions.
NB. Windows 7 Ultimate, x64 (but 32-bit IE8).