1. Join one or more channels.
2. Activate the Status-window.
3. Open up mIRC Favorites, and type in the name of one of the channels you just joined.
4. Press the "Join"-button. mIRC will now activate this window, however the switchbar will still show the Status-window as being active.

confirmed.

It also does this if you simply select a channel from the favorites dialog (instead of typing it).

It does not have this error if you select the favorite channel from the favorites menu.