I have a load of Windows computers which Boinctasks works with fine. But I have some oddities - a 2nd instance of Boinc on the same machine, using a different port. And a Virtual Linux machine (Oracle Virtualbox) on the same machine (different IP). Both these don't work with the "Extra, boinc prefs" menu if I'm in the task tab and select one computer on the left - instead it shows the prefs for a different machine, possibly the last one I looked at the preferences for. If I go into the computers tab and select one computer not on the left column but in the main section, it gets the right one.
Added to the todo list