I am using Norton Internet Security 2010 and IE 8.
I turned on Identity Safe, but I don't like how it works (sorry, I just don't), so I turned it off again.
Since then, IE will not remember passwords. I can change my settings each time I turn on the computer, but it will not remember those settings because the Apply button is greyed out. This has happened only since I turned on Identity Safe and then disabled it.