For what it's worth, I've been on other vBulletin-powered forums which suffer from white screens.
I think DJ-CHRIS is right, it must be some kind of bug or glitch which is causing PHP to bale when you pass data to it. That problem's not just confined to CF.
Personally I think vBulletin itself has a lot to answer for, you have to use PHP, MySQL which are fair enough, but Apache? That's outdated, insecure, clumsy garbage; newer versions of IIS run rings around it... but try getting PHP and MySQL to play happily with that...
I guess it's all PHP/MySQL so that the Linux crew won't get upset over it, if it was SQL Server/ASP.Net that would require David to install MS SQL Server which costs a fortune (the Express version is free but not nearly scaleable or durable enough for a job like this).
As I said in the other thread, I think an update would be a good thing but it has to be cost effective. VB
3.7 is expensive and 3.6.9 offers no real benefits for the time and effort it would take for David to set it up. I vote we stick to what we have for now, but David needs to maybe look at his security options and upgrade PHP/MySQL if it doesn't break anything; those are free and IMO there's little excuse for not having them if there's improvements to be had.