[markbolyard]

Are you on shared hosting, a vps or a dedicated server? If you are on shared or a vps, I would think it's a memory issue. On a dedicated, it could be the same thing but one thought would be, ask your host to increase the amount of memory on your server (even if you have to pay for it. You could always downgrade next month if you can't afford more ram) If not, my other thought would be, download a mysql backup, install a local copy of vbulletin on your computer using xampp or the like and create a "offline" version of your site, make all the changes you need locally then restore to your live site.

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BTW, what version of vbulletin are you running and what's your forum URL (can PM if you don't want to display it publicly).

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Originally Posted by Head-Nod.com

If I could only delete all unmoderated posts, and all posts by deleted users, it would free up about half my post table, but I don't know how to do that without it crashing!

Have you tried the prune function in the admincp under threads and posts? Your post by deleted users (those users should be Guest now), you could prune those, you can prune threads in moderation... something to try.