if you are running php newer than 5.3.19, then you'll have this problem.
i recommend not running php 5.4 for now

My ISP has PHP Version 5.4.15 on Linux/Apache. They upgraded everybody last year from 5.3 so no hope of going back.
So, no resolution to this Buggis Majoris still?
It's only my own Admin posts (especially Copy & Pastes from TextEdit and anything with UBB formatting including Bold, Italics that gets screwed on Re-editing).
Creating posts etc. is fine, as Steve Bolt has stated earlier.
ONLY SOLUTION: Change UBB Code pop-up to UBB + HTML pop-up below it, and bring Copy & Pasted text in as Plain Text from Apple's TextEdit