Today Lync 2011 decided it was not going to log in. Each time I tried I got an error about the oc_keycontainer and a request for my password.
I tried just deleting all the oc_keycontainer entries from Keychain Access, but still no luck.
It turns out it’s necessary to also delete the OC_KeyContainer_[username] file from ~/Library/Keychains
Re-launch Lync, and all should be good.