I’ve got the same issue except it’s even worse, bin may disappear altogether… (Avid 5.5.3.3 on OSX 10.6.8)
I’ve made a very detailed post on Avid’s forum: https://community.avid.com/forums/t/109169.aspx
Avid says they’ve seen this problem on a few OSX systems around the world but they are still unable to track down the issue…
Have you found a solution or a workaround?