To return to your normal IM window:

1. Click the IMVironment button located at the top of the Instant Message window where you usually type a message.
2. Select the No IMVironment option at the bottom of the menu.

Back to normal!

To disable IMVs:

1. Click the Messenger menu and select Preferences.
2. Click the "Messages" category.
3. Uncheck the "Enable IMVironments" option.
4. Click OK at the bottom of the window.