Ironically, Macworld forum member HappyMac is a little unhappy with his Mac. He writes:
Something about Keychain Access is messed up. I’ve run the repair utility and searched various forums for help but nothing helps. I would like to delete Keychain Access and reinstall a fresh copy. How do I do this?
Quite honestly, I think you’re putting the cart before the horse. Before tossing out the Keychain Access application I’d run through the steps necessary to cure whatever ails your keychain.
For those tuning in at home, the first step is to launch Keychain Access and from the Keychain Access menu, choose Keychain First Aid. In the same-named window that appears, make sure the Verify option is enabled, enter your administrator’s user name and password, and click the Start button. If any entries appear in red, click the Repair button and click Start again. With a measure of luck, the red entries disappear and you’re left with nothing but black entries and keychains that perform as they should.
If this doesn’t happen and you continue to have keychain problems, quit Keychain Access, go to your user folder/Library/Preferences, and move the com.apple.keychainaccess.plist file to the Desktop. This is Keychain Access’ preference file. If it’s corrupt it could be causing the problems you experience. You needn’t fear losing the data stored in your keychain when you move this file. The com.apple.keychainaccess.plist file doesn’t contain any of your keychain data.
Still having problems? If it's only specific items that are causing you grief, open Keychain Access and use the Search field to locate related items. For example, if you're having problems with MobileMe remembering passwords and login information, search for .mac in Keychain Access' Search field and delete those entries by pressing the Mac's Delete key.
No good? If you have a backup of your keychains (as you would if you’ve run Time Machine), quit Keychain Access and locate those backed up keychains (found in your user folder/Library/Keychains). Try substituting them for your current keychain files (move the current ones to the Desktop should you need them later).
If this does no good (though I’m not sure why it wouldn’t), launch Keychain Access, choose Preferences from the Keychain Access menu, and in the General tab of the resulting window, click the Reset My Default Keychain button. You’ll be prompted for your administrator’s password. When you choose this option your old default keychain (which is likely the “login” keychain) is renamed and a new empty login keychain is created. You do this simply to get a fresh start. All your old keychain entries will be gone, so we’ll hope that you’ve written down your passwords and login information so you can reenter them when prompted.
If you’ve failed to write them down and you’re the adventurous type you could try copying keychain entries from your old keychain to the new one. To do this, go to your user folder/Library/Keychains, locate the login_renamed_1.keychain file, and double-click on it. This will launch Keychain Access (if it’s not already running) and cause the login_renamed_1.keychain item to appear in the Keychains list. You’re now at liberty to select items in the old keychain and copy them to the new login keychain. This could be helpful if the old keychain itself was the problem rather than the entries in it. (Of course if the old keychain is that mucked up it’s possible it won’t appear when you double-click it.)
My hope is that somewhere in this mishmash of advice a solution exists.