I once installed Opera by adding their repository to my sources.list:
deb http://deb.opera.com/opera/ stable non-free #Opera
Since then I get regular updates via the usual "apt-get update && apt-get upgrade", the last some weeks ago to Opera 11.51. Since then, Opera regularly (once every some days, sometimes more often) crashes (browser window disappears, and then the error reporting dialog comes up). (The same happens on OpenSUSE, where I had the upgrade last week, thus it is not Ubuntu-specific.)
This just occurred again (while I was typing an answer to a question on another Stack Exchange site) and I don't want to tolerate it any longer.
Is there an easy way to downgrade to an older version (like 11.50, which didn't had this problem), and still have the possibility to get the upgrade query when the next version comes out (which hopefully fixes this)?