I reinstalled my Mountain Lion, and since then Adium keeps asking for passwords on every Adium restart/startup. Understandably, this is quite annoying.

I’ve tried the following:

  • readd the accounts
  • reinstall adium
  • run keychain first aid
  • check this
  • reboot
  • pray to the gods, old and new
  • check console (which is spawning a thousand million errors about read access denied, but Google told me it's a known Mountain Lion bug)
  • update to Mountain Lion 10.8.2
What I did to solve it (I believe):
  • Uninstall Adium completely (tada)
  • install 10.8.2 (well, I happen to reboot just after uninstalling and reinstall Adium, so I'm unsure whether the first or 2nd point was most useful).
And it's now working correctly. So far.

Downside: have to readd all accounts (Google 2-step verification fun, and time to delete those old accounts (xmpp/icq) where I forgot the passwords), and reset all your settings.

Edit: it has been confirmed by Adium it’s enough to just upgrade to Mountain Lion 10.8.2 to solve this problem. No need to delete all your settings & accounts like I did… ;)