I'm running a PHP code widget (to run a customized RSS feed parser) and when I assign a Widget Logic statement to it, and click save, it pauses for a minute then completely DISAPPEARS from my Admin manage widgets page. (And disappears from my site too).
Hmmmm... I want to replicate this problem that plagued me for several hours yesterday, and now it appears to be working... So, I will leave this as a resolved question in case anyone else finds such a similar quirk...