Why IM is an IMperfect Medium of Communication!

I had a conversation with a friend in SL in IM Monday night that went badly. We were both tired--exhausted from long hard work days. We both wanted to at least say hello, but we were both also ready to drop and wanted to go to bed instead of into SL. Instead of a nice chat, we both left felling frustrated for different reasons, each thinking the other was being hostile. The conversation began like this:
me: I was just waiting for you to say I'm sorry
him: what?
me: sorry I can't play tonight
him: oh sorry I can't play tonight

And here's the confusion. He heard me ask him for an apology from him for not being able to play and gave it, but it made him upset that I was angry. I was offering an apology for not being able to play and I thought that he was echoing my words to show that he had understood and accepted.

The basic limitations of SL chat or any IMing for that matter are in the lack of emotion that is conveyed. We add emoticons or acronyms (LOL, IMHO, etc) to compensate for that. But the thing that really clarifies for a reader what the writer is saying, where the intensity and the inflection goes, is punctuation and full sentences. Not only do we avoid excessive punctuation in IMs, but we also pare our words down. This makes for fast communication, but it also makes things we say able to be read in multiple ways.

What I said was really supposed to be:
"I was just waiting for you [to arrive], to say [to you that] I'm sorry. [What I am] sorry [about is that] I can't play tonight." (Subtext: I am really missing you and want to play but am too tired, please forgive me.)

What he heard was:
"I was just waiting for you to say [to me] 'I'm sorry,' [I want to hear you say:] sorry I can't play tonight." (Subtext: I am pissed and you owe me an apology.)

BIG difference, no?

Unfortunately the conversation took a downward spiral from there, with both of us on the defensive, both of us clueless as to why the other seemed angry. Fortunately after we had slept on it (albeit badly), and once we had compared notes, we figured out the miscommunication and really apologized to each other and laughed about it. We also came up with some rules for IM chat.

1. Don't assume the person who loves you and who you should trust is angry. If you are confused, ask them. Ask for clarification of the words just sent. ("Did you mean to say...").
2. Don't expect the need for clarity to be one-sided. People who know each other well may be able to read between the lines, but you can't depend on that. Ask if the other party understood your words. They will appreciate your concern.
3. Write in full sentences and use punctuation. Really. It may be slower in the short term, but it will save time and trouble in the long run.
4. Trust each other. Always be honest when you are bothered. Chances are there is something being miscommunicated.

So, out of curiosity, any of you out there have this same problem? What are your solutions? Your rules for IM chat?