The only reason I could think why you got this error is if to much data is being entered for one of the Poll Choices.
Check your SQL Server database that in the table 'tblPollChoice' that field 'Choice' allows a minimum of 80 characters.
Although no changes have been made to the Forum Polls in the last year there have been three releases in the last year which have added new features and fixed various bugs. The page below has the new features and bug fixes of the various releases:-
http://blogs.webwiz.net/web-wiz-forums_cat2.html