I'm having problems pruning topics in UBB Threads 7.1.1 too. (I tried it for the first time earlier today.) I don't know if it's been updated in later versions, but it usually just times out after 30 seconds...and that's when it's only trying to prune about 50 topics. Our board has 580,000 posts, by the way, consuming 1GB of hard drive space. I'd like to suggest that the pruning feature be tweaked for the new 7.3 version to make it useful for people with large boards.
