Here is a pointer to my request for feature for this very problem submitted back on 20 May 2010.

ideas.limesurvey.org/ideatorrent/idea/153/

I experience the same problem, "Database error; can not activate survey, too many columns" The questionnaire is not that large in the sense of many questions (about 35) , but has some questions included whith a long list of multiple options (array number). I was very much surprised by this error message as I also did not get any message in advance that this might cause a problem. What I'm looking for now is a practical solution. Someone can help me out? Thanks in advance.