My text window, when I open up to read or send a new text message, says "Connecting to Chat" up top. I never activated this feature, and I see no place to inactivate it.
Also, I use my camera, the one thing on this phone that works constantly, to capture my expense receipts to place on a report. I snap, email them to my work address, and add them to the report. Today, when doing this, I received errors stating that they could not be sent. I found older messages that I know were sent successfully, resent those pictures, and the same error came up in my inbox, stating that they could not be sent, either because of size or other reason. I then checked my work inbox, and, lo and behold, all of the messages were there! This is unacceptable - I'm glad that they were sent, but what's with the error?
Simple, you may not remember activating it, but I figure that Facebook Chat is enabled in your Messaging app.
When you open the Messaging app, swipe over to the "Online" pivot, at the bottom of the screen in the App Bar, select "Status." Make sure it's set to "Offline."
Additionally, expanding the App Bar will reveal a "Settings" option. Open "Settings" and make sure that "Use Facebook Chat" is disabled.
Hope that helps!