Har samma problem. Såg detta nyss.
I got this response from Sam at .Mac support and I'm finally able to sync keychains accross multiple Macs again! Here are the instructions (just make sure you merge your keychain when prompted on the first sync - I replaced them with the keychain on .Mac and that caused all kinds of problems!!)
How to back up and restore your important Mac OS X 10.4 files
<http://www.info.apple.com/kbnum/n301239>
After backing up important data, please proceed with the Master Keychain Reset procedure. To reset the Master Keychain password, follow these instructions:
1. Open the Terminal application. Terminal is located at /Applications/Utilites/Terminal.
2. Type the following command:
/System/Library/Frameworks/SecurityFoundation.framework/Versions/A/Resources/kcSync.app/Contents/MacOS/kcSync -reset
3. Review the text entered in the Terminal prompt to make sure it exactly matches what is listed above.
Note: You may find it easier to copy the complete command provided in Step 2 and then paste it into the Terminal application at the prompt as opposed to typing it.
4. Press the Enter key on your keyboard to execute the command
After the command has executed completely, you should receive feedback in the Terminal similar to this: "removing /Library/Keychains/.syncinfo/login.keychain.syncinfo.plist was successful."
5. Quit the Terminal application.
You may need to re-enable Keychain Synchronization an any synchronizing computer after taking these steps. Additionally it is possible that Keychain will prompt you to update your settings in a variety of applications. If prompted to update you settings, click the update button.
After following these steps and then ensuring .Mac Sync has been enabled in your .Mac System Preferences, you should be able to Sync normally.
http://www.macosx.com/forums/mac-os-x-system-mac-software/263980-kcsync.html
http://discussions.apple.com/message.jspa?messageID=1193854#1193854
