I was testing a custom 404 page this morning on Chrome when instead of seeing my page I got the following
You can turn it off on YOUR computer but the problem is that you can't do it for your users. This means that if you use your 404 pages to try and re-direct your users to the right link or even revenue via ads then you loose out! It would be nice if you can set a HTTP header or something along these lines to tell Google to not be clever but till now
To turn this off on the Mac go to Chrome > Preferences > Under the Hood and deselect "Show suggestions for navigation errors".
For other OS instructions check out http://www.google.com/support/chrome/bin/answer.py?answer=95671&hl=en