A client sent this one to me today as good blog fodder. I agreed, so here it is!
When he went to Site Settings / Site Settings / Content and Structure from the root site, he got the “Arithmetic operation resulted in an overflow” error:
After some sleuthing, they realized that there were two lists in the root site with exactly the same name, same number of items, same modified date/time, etc.
They had been doing some migration of content from SharePoint 2003 to 2007 and ended up with a duplicate list. Deleting one of the duplicates solved the problem. I’ve also seen mentions out on the ‘Net about duplicate views generated in the same way causing the problem. Both of these situations could also be fixed from SharePoint Designer by looking at the folder view of the site and doing the deletes there.
They are running 2007 RTM (don’t even ask), so the error message may well look different in a newer rev, but it certainly doesn’t point to anything useful in this case. I’m not even sure that it’s possible to make this happen any more, but just in case someone else runs into the error, it seemed like a good one to (b)log.