I received the following error message:

"Arrgh! The page has been corrupted. If you are running security or firewall software, you may have to disable it. Learn more"

The help page says I might have Norton antivirus software which causes this (I don't). The error appeared only once, so I can live with it...

I had it while running XP and Knoppix, and Debian. I don't have Norton. I've had the message numerous times times. I sent an email to supportgoogle.com. I received a auto-generated reply that Google couldn't answer this question. I should go to the help page to read about the problem. It continues to happen.

My solution to the GMail Corrupted Page Problem
For me, it happens on the spam page.

At the bottom of the page, click on "basic HTML."
Go to the spam page. Manually select all the spam. Delete forever. Switch back to "standard" mode.