Error in iCal: The server did not recognize your user name or password for account “Gmail.”

To keep my iCal up to date on two computers, I export an Archive in one and import it to the other. Yes, I know I should use the Cloud, but humour me.

Export of iCal from my MacBook Air (OS 10.7.5) no longer works when imported to my desktop (OS 10.6.8). It returns an error saying "The server did not recognize your user name or password for account “Gmail.” Make sure you enter them correctly."

After dismissing this dialogue box twice (it offers no other options, iCal crashes.

I've turned off the option on my MacBook that asks to use my Gmail account, but since I can no longer launch iCal on my desktop, it can't import new data. How can I clean out the brain of iCal on the desktop so that it will open -- blank -- and perhaps accept a new version of my iCal data?

Thanks,

Bruce