Currently, I'm doing the opposite of what you're doing. Instant messaging was turned off for the longest time but am now using it more and more. I view IM as more of a distraction than anything. I'd rather fire off an email for most stuff but instant messaging is instantaneous. I suppose that's my problem with it people expect you to drop everything and reply
Right Now
Facebook Messaging is the worst. Facebook is like a universal platform. There's no more "Do you have ICQ, AIM, YIM, etc?" - It's "I'll catch you on Facebook." I have a few clients on Facebook a couple of which are to lazy to launch Skype so I can sign out of FB. The problem is two fold. a) Clients randomly pop up asking questions like I'm supposed to drop everything and figure it out even at noon on a Sunday. b) Friends pop up and say Hi while I'm trying to work. - It's not that I don't want to talk to these people it's that I'm busy. How many times can you say I'm busy before people feel like you're giving the cold shoulder.
I'm going to have to start grouping people and turning off chat availability to friends vs. business.