There are two solutions to the the extra buttons and wheels not working. Either use the "mouse registry file for gamers" patch that Logitech has on their site (its on the same page as the mouse drivers), but the patch isn't perfect.
"A possible side effect is that some "double scrolling" may occur in
some applications that can receive wheel messages from both
DirectInput and Office compatible wheel messages." is what it says in the README for the patch.
The second option, that i use, is to simply press ctrl+alt+del and end task "Em_exec". This will cause all settings made in Mouseware to stop working in windows(meaning extra buttons and wheel). But in games, the buttons and wheel will work perfect!
So do this whenever you're gonna play a game requiring the buttons and wheel. "Em_exec" will reappear the next time you restart, or run the "Mouseware Properties", accessible in the Logitech Mouseware folder in the start menu.
was that thorough enough?