[whpalmer4]

The keychain entries won't show up as created by OmniFocus in any obvious way -- mine show up as regular internet passwords for idisk.mac.com (username) or idisk.me.com (username). You can flush out any use of an existing keychain entry by locking your login keychain, then trying to do a sync in OmniFocus. You'll be prompted to supply a password to unlock the keychain. Another approach would be to create a new user on your computer and see if your problem persists there.