One of those problems that really doesn't have a nice canned answer...
How many people would be left if you tossed out all the problem players?
That's probably not a viable solution as most of us don't have waiting lists or game with people we feel too committed to. Sometimes though you just have to accept that your friends can't be your gaming buddies.
You may just have to seek out slow transition steps to move them over to a new way of thinking. I do a LOT of asking when I GM.
- What do you do now?
- What do you think of this?
- How does [PC name] feel about this?
- What do you plan to do next?
- What kind of food does [PC name] go for?
- So when you go into town, other then meeting the Wizard -where do you plan to go?
Ask a -lot- of leading questions. The kind that don't have a yes or no answer. This forces them to figure out an answer, and in time they will just start roleplaying.
Also toss out a lot of disconnected wierdness:
- The guy selling apples looks familiar.
- The barmaid winks at you.
- The kobold nursing a beer near the Bard's stage seems to be muttering in old draconic and moving twigs and stones about on his table.
- You get this funny feeling when you enter the woods.
- As the Orc charges you, he cals out your family name.
- When you wake up in the morning, all your possessions have been moved to where [second PC's name] possessions where, and hers to where yours where.
and so on...
This kind of stuff gets their attention, and unless they're log-toads they're going to start reacting to it. It doesn't have to make any sense or have any connection to the module or plot - but the questions they ask and the things they do once you toss it out will get some kind of ball rolling.
My other main tactic in GMing is the Spot check, my players tend to burn out dice on spot checks alone - I probably get ten to twenty of them out of each player per session in my Mutants and Masterminds game. It's a lot of fun to see people burn Hero Points on them. Spot checks and questions are how I write my scenerios. If they rolled high, I consider putting something there for them to see. The -what- being based on how they were answering the questions I asked earlier.
Another trick is to 'acidentally' read something that's meant for DM eyes only as if it were boxed text...
"The room has a chair, old maplewood desk, search DC 20 to see the key to the locked door under, oh! Ooops...."
The players will now have this guilty desire to all say they're checking out that desk... You've gotten them to do something, and you can pretend it was an accident. Chances are they will try to hide it by saying they're "searching everything in the area" or other little phrases they think are so clever - which will allow them to encounter what you really wanted them to get involved with.