this is Kinda a bug. When mirc is set to minimize to system tray, and you are useing ultramon for a second task bar on aditional monitors, mirc will not remove itself from the taskbar when minimized by double clicking the taskbar entry. (wordy i know.)
Mirc will only remove itself from the taskbar if you click the underscore or right click the taskbar entry and click minimize. this is NOT an ultramon bug beacuse other applications dont have this problem.