Hey, I have had the same issue with my icloud account. I have been on the phone to an Apple senior tech advisor and this is what he told me to do:
open terminal and type:
sudo chmod -R -a "everyone deny delete" ~
hit enter
enter your password and watch terminal resetting all the permissions for the entire content of your HD. Once done close terminal and restart your mac whilst holding down the option/ alt key. If you have Lion installed you should be able to select the recovery partition, otherwise insert your OS Lion install DVD and choose it as your start up volume.
from the menue bar, I can't remember which menue item but looking through all of them, one will give you the item 'Terminal' and you open that. Once in the Terminal app type:
resetpassword
hit enter
a menue will pop up from which you choose your startup drive (Macintosh HD). Ignore the reset password section and just click on <reset home permissions and ACL>
you might have to enter your password again.
Grab a cup of coffee.
When done restart your Mac and your problem should be sorted.
I take, however, no guarantee but it worked fine for me, except for my time machine. It went to backup my entire HD because every single file was altered in the process. No big deal if you have a mighty large backup drive though..
