onload event properly fires once
the page is done loading.
onload event has not yet fired in the 0ms
since this page started loading. It normally fires in less than 100ms.
One known problem occurs in Firefox 3 on Windows with an old version
of the Skype extension for Firefox installed (version 2.2.0.89 or earlier).
In this configuration, the onload event will never fire on this
page. The same problem will occur on any page hosted on Google
domains (e.g. maps.google.com, www.google.co.uk).
As a result, this bug can break Google sites like like Google Maps
that rely on the onload event to work.
The problem does not seem to occur on non-Google domains.
To fix the problem, either upgrade to the newest version of the Skype
extension or disable/uninstall the extension.
For background see this thread, this thread, and this thread on the Google Maps help forum and this thread on the Skype help forum.