I don't know about Firefox and other similar browsers, since I use IE exclusively; but recently I thought I'd lost all my bookmarks because I accidentally (well - on purpose and then forgot I'd done it) switched the view from "Favorites" to "History," and when I deleted browser history while closing the session everything (where I thought I'd see Favorites) went blank.

As for toolbars, IE shows the URL box and the bar that contains it, and a bunch of kiddy-toy icons that I'm too dumb to use effectively; but has a "Tools" button where you can select display of the "Menu Bar," which is actually unambiguous and useful (for me).

My Norton NIS also adds a search bar, and although I don't use their "Norton Safe Search" much, I leave it up because it gives me a flag warning if I even hover on a link to an "unsafe site."

Add the Google toolbar, with about 150 choices for how yours might have been configured, and when you say "lost my toolbar" it becomes really ambiguous.

Other browsers and accessories quite likely have lots of other similar choices and variations. A very specific description of what disappeared (and what may have replaced it, even if it's just "a blank space") might help someone to recognize what's happened? e.g. What labels/icons went away?

And especially with "mix-n-match" AV, antiPhish, AdBlockers, etc, any one of these may have decided that perfectly innocent "add ons" and/or cookies are something nasty, in which case the problem may disappear next week when you get the next updates.

John