So after I updated my macbook and iMac, I go to sync with my .mac account. The iMac works just fine with .mac and syncing; however, the macbook pops up "Unknown Validation Error. Your .Mac member name or password may be invalid. Please enter a different name or password." I've reset my password and can still log into .mac through the iMac and I can even log into my .mac account through Safari on the macbook. I spent 2 hours on the phone with applecare yesterday moving preference folders around and restarting a million times. Finally, applecare have be archive and reinstall 10.5.2. That worked fine and .mac was syncing beautifully. I was then told to update back up to 10.5.3 and now the same problem appears. Suggestions? Help? Thanks!