OK Ripsnort, I think Digerati was just trying to make sure you are actually in IE9. IE9 does not have a "bookmarks" section, it has a "favorites" section. Firefox calls theirs "Bookmarks" so since you used the word bookmarks he was merely trying to figure out if you were really in IE. Sometimes users have no idea what browser they are using and some don't even realize the difference between a browser and the Windows OS. So if you are talking about bookmarks in IE9 please just call them "favorites" so Digerati will be happier.
I did some research. I just made my menus so long that they had to scroll in both FireFox and in IE9 and in Firefox my scroll-wheel does work and in IE9 it does not (even with KatMouse installed). WizMouse may attempt to add the scroll wheel functionality but there is no guarantee it will be successful and it sounds like your issue means it isn't totally successful w/ IE9 favorites.
Also, the scroll wheel may have worked in older versions of IE (and as I said, I know it works in FireFox) but apparently IE9 isn't allowing it and KatMouse can't help (EDIT: WizMouse might help but it may depend on your mouse drivers and settings). Browsers change stuff each generation with the primary purpose, as far as I can see, of angering people and, if you say it worked in older versions of IE (like IE6 in XP), then this may have been one of those unwelcome changes.
Your choice is a different browser or to make your menus shorter utilizing folders, as I offered as an alternative, so that the entire menu fits on one screen. Other than that information, I'm afraid in this case, I can't help you.
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I also retract my idea to try the performance setting for smooth scrolling; I know it won't suddenly make IE9 favorites work with a scroll wheel which is what you want.