ok - when someone in my Plurk friends list is highlighted in pink, and when clicked on says "can't find" - and I KNOW good and well I've seen their posts..what's going on? Am I muted? Are they? 
that's a good question
If it's what I think, it means that they have disabled their account.
It's not deleted, but until they enable it again, you can't see their posts or even access to the account at all.
