Problem upgrading to 3.2.1 from 3.1.1

I clicked on the “updates” tab, then “update automatically” the system returns the following error:

“Downloading update from http://wordpress.org/wordpress-3.2.1.zip…

Unpacking the update…

Could not copy files.

Installation Failed”

Any suggestions on why this is happening and more importantly, what I should do to fix this issue?

Thanks!!