I had a similar issue - in my case system preferences would hang on trying to access iCloud from its own pref pane or through the accounts pref pane. I solved it by deleting all files from the following folder:/Users/<MY HOME FOLDER>/Library/Application Support/iCloud/AccountsI was then able to get into the iCloud preference pane, where it asked me for my new password. After giving it, all was working again.It sounds like you'll have to delete the files while running OS X from another partition.
Topic:
App & System Services
SubTopic:
Core OS
Tags: