Solution to Keychain update hang on MacOS X

MacOS X has fewer weird problems than Windows but it's not totally without issues. For the past month I've had a terrible problem where anything that needed to update the keychain would kill the machine to the point of needing a reboot.

Normally, I don't need to do much maintenance but I tried the following:

• Booted from my install DVD and ran disk utility (that did fix some problems including a file I couldn't previously delete)
• Running Utilities/Keychain Access and getting it to repair my keychain (it found nothing wrong)
• Deleted keys with Keychain Access that were used by apps that gave me trouble.

In the end I found a pointer on an Apple mailing list to this article. In the end all I did was:

• sudo mv /var/db/CodeEquivalenceDatabase /var/db/CodeEquivalenceDatabase.old
  
• reboot

And all is well.

Reading around, it seems this is a rare but repeated problem.