I recently was able, in my case, to pinpoint one reason why I was losing my Carbonite Quest Tracker window. I had no need to enable the Warehouse feature so I went under Option>Modules and deselected the Warehouse checkbox. However I closed the window and typed /rl. When I did that the Carbonite quest tracker window disappeared. I had to delete the Carbonite SV file in order to make it appear again. Then I repeated the process as above but this time I left the Modules window open and clicked the Reload UI line and all is fine after that. Something to be aware of.