http://sn.1w6.org/file/mk-20141004T143532-gbw86l4.html

@mk SUCCESS! Indeed, *purging* the old version of VirtualBox was the answer - but that took some doing because - having close Synaptic - it had disappeared from view. Some ddg-ing about purging brought the solution - and apart from a list of uninstalled programs that had 'virtualbox-4.2' there also was something called 'wine-bin'. Even before purging the old VirtualBox, I *reinstalled* wine-bin (it automatically took the latest, not the uninstalled version), and that included something called 'wine32' - precisely what q4wine had been grumbling I should install (but could not find)!