You may also find that the recent files history in the quantarc files can fill up, and get quite large in size.  You may be able to remove old files in the lists (Make sure you make a backup copy first).  I cannot remember the exact settings, but there was some discussion on the list about a year or two ago. If you don't have any real customisations, you may want to move your quantarc files to a safe location and start quanta fresh.  I say move, because all your settings are in this file, and deleting it can cause grief if you have any settings you want to keep.

Hope this helps