Rated 3 out of 5 stars
the redirection could be caused by your user-agent setting which probably contains the string MSIE. Sorry, but usually those visitors of my pages are spam robots.
Thank you for the suggested formfill configuration! It does exactly what I need.
I also tried miscellaneous settings to exclude suggestions not starting with typed letters, but had no success. Anyway, I found that setting boundaryWeight to e.g. 100 (while bucketSize is set to default) will prefer suggestions starting with typed letters. Those suggestions then are placed on top of the list.
The Searchbar Autocomplete Order add-on indeed only shows suggestions beginning with typed letters. But it even excludes multi-word suggestions where the matching word is not at first position: e.g. if you type co, it will not(!) match "about config" but it would match "config about".
However, Searchbar Autocomplete Order no longer works with Firefox 4, they completely rewrote the suggestions code and I think it's a quite big deal to update the override code of the Searchbar Autocomplete Order add-on.