When using GMail I sometimes get the following error message:

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

This is a bad error message for a number of reasons.

• They are telling me that I may have to disable my security, or firewall.
• The error message is simply: The page has been corrupted. What does that mean? Is it involved in organized crime? money laundering? it doesn't sound good to me, the last thing I want to do is turn of my security or firewall. Error messages like this scare the crap out of non technical users. This is the kind of error message that when my parents get, I receive a phone call.
• Arrgh! - also would scare my parents. I'm all for error messages that show a human side, but this gives the impression that Gmail is mad at me.

The thing that gets me is that this is not a security or firewall issue for me, it happens randomly, so I would guess that this is probably actually due to a bug on Google's end.

Another thing - my parents do actually have a gmail account, so lets not think that Gmail is only for early adopters. Plenty of non technical people are using it.