When Gmail insists on switching to the low bandwidth version

Today, for some reason, gmail all of a sudden insisted on using the low bandwidth version of the app because it said my browser (Firefox 3) was not supported. This was happening on Google Apps Mail and regular Gmail.

I found that changing the language setting to English US did not help.

What did help is using this URL:

Regular Gmail

https://mail.google.com/mail/?nocheckbrowser#inbox

Google Apps

https://mail.google.com/a/yourdomain.com/?nocheckbrowser#inbox