We deleted the Polls plug-in folder from our server and the Forum is back.  We can live without Polls, but would prefer to have that feature.  So, any ideas on how this might have happened, might help to insure it doesn’t again, and we can try reinstalling.

are you sure the polls folder was named correctly?? polls vs polls1 or with some other number? the wp uploader can incorrectly add a digit on there in some cases…

You nailed it Mr. Papa!  It did have a (2).  I had uploaded it once before, but after activating it, it wasn’t working.  So I deactivated it, then deleted it, then uploaded it again.  So, even if I delete in the admin section, I’m thinking that I need to delete the folder via FTP as well, or future uploads will tack on a number.  Do I have that right?

yes, correct… when wp uploads a zip file, it extracts it into your uploads directory… when done, its supposed to remove it but sometimes it cannot because of permissions… so if you do another upload in same month, wp will append the numeric number to the extracted directory…  and causes errors… 

luckily a simple rename via ftp or ssh of the uploaded directory will correct it…