Issue: 500 Server Error on some Threadlisting Pages

VaultWiki is causing blank pages to appear on certain forumdisplay threadlisting pages. Here are some sample links:

http://www.aelyria.com/forums/spellbook/index5.html
http://www.aelyria.com/forums/registrar/index4.html
http://www.aelyria.com/forums/gazetteer/index6.html

1. This is definitely being caused by VaultWiki. Disabling VaultWiki instantly allows these forumdisplay threadlisting pages to appear.

2. This is not caused by any other vBulletin add-on. vBSEO was initially thought to be the culprit, and I had the vBSEO Team on our site. They disabled vBSEO and can still reproduce the problem.

3. Our php.ini has 256M of memory allocated, so, memory should not be the issue.

4. Guests do not exhibit this problem, but all logged in users do get the 500 Error/Blank Page.

It appears to occur on wiki-type forums when you are looking at separate pages of the threadlistings. Here are the forums of the above corresponding "blank pages":

http://www.aelyria.com/forums/spellbook
http://www.aelyria.com/forums/registrar
http://www.aelyria.com/forums/gazetteer

The first few "pages" of threads are displaying fine. But once you get to the fourth or fifth page, you start getting Internal Server Error 500's with blank pages. There are no relevant error reports appearing in our error logs to make a determination about it. That said, I was not able to reproduce this on the parent-forum of the namespace -- these forums were all sub-forums of the parent-forum. I could navigate the parent forum's threadlisting just fine.