Shoutbox

Do you have Kiwee, GDI++, MSNShell or ThreatFire installed?

These are all known to be incompatible with Messenger Plus! Live and can cause the kind of problem you are describing.

Even if you don't think you have any add-ons, check your Add/Remove Programs as they may have become installed without your knowledge.

Also, check your Messenger Plus! Preferences & Options

Click the 'Conversation' tab along the top, then the 'Formatting' tab along the side and check that the options for using codes in conversation windows are ticked