Problem with "Generator" when downloading purchased items
I've had to get a new MacBook which is now running OS 10.8.2 with iTunes 11.0.2.
Software Update confirms that everything is up-to-date.
I have set everything up successfully, authorized my new computer and deauthorized my old (stolen) ones.
I am now in the process of trying to download all of my previously purchased music and apps from iTunes. However, every item I download produces the error message:
"There was an unknown problem with "Generator". An unkown error occurred (8268)."
This happens whether I download items individually or simultaneously (when I just get multiple error messages). This is intensely frustrating and I can't find any information on this in Support.
Can anyone offer any advice?