>Possibly. I have another computer with IE8 and no problem there. But there so many settings that it is possible that one of them got set/unset and it causes this weird problem.
>I tried IE9 on another computer and found the interface very different from IE8 and wanted to avoid upgrading on this (my main) computer.

Since IE8, or maybe the one before, its behavior may change after times. So, lets say you work with it for months on a specific Web site. Then, the next day, you are forced to enter it in the Trusted Web sites list in order to contnue to work with that site. And, nothng changed. It is just the way it is. There are some background actions that run in that browser which I never understood. In most of the times, uninstall and install will do the trick. But, that assumes nothing has been stored locally as we might run into the same situation after.