It is superbly annoying when I have to be friends with someone who I can't talk to.
Usually it's a combination of them being unwilling to listen and unwilling to be wrong/have something pointed out that is completely obvious. I can see where the second comes into play- I hate being wrong and I hate the obvious being pointed out (I'm more frustrated with myself than them, though), but sometimes one needs someone else to see the whole picture, someone who isn't so close. They may see only one tangly path out of where they are, but because I'm not so close to the problem, I can scout out paths that are simpler, and may lead to less hurt.
I've got to put a few rules down, it seems.
1. Avoid any kind of sticky subject. This could be anything from religion to relationships to stories and writing (who thought that innocent writing would be a sticky subject?)
2. When trying to help (even if I'm asked to) say nothing but "mhm" and "I agree" and suchlike.
3. If one of these friends-who-I-cannot-talk-to is being totally irrational, do not attempt to rationalize them, as they may do a number of things that include cursing at me, swearing that I'm on "their" (whoever the enemy of the situation is) side, and insulting various aspects of me.
4. Smile and nod, or look sympathizing, or indifferent, depending on the situation. This can save my life.
5. When tempted to talk seriously with this person (which previous serious talks have produced unwanted results) write it elsewhere or talk to someone else instead.
EDIT: 6. Don't talk about taking naps or anything of the sort because they seem to be obsessed with telling me I shouldn't sleep so much, when they know nothing of how I've been sleeping this past week, month, etc.
(Rules are subject to change, mostly additions as subtractions would be foolish and probably produce undesirable results)
*sigh* Can you see me following these rules, as open as I am?
I thought not. But I'll try.