I'm testing exactly the same web-page on two different machines, which each have Internet Explorer 7 installed.
One machine renders the page without errors.
GOverlay is undefined.
Can anyone think of a reason this would occur on one machine but not on another?
Before you ask, yes, I've thoroughly cleared the cache, deleted 'Temporary Internet Files' and restarted the browser on both machines.
Are both the machine's in the same physical location? (i.e. one could have a faster connection speed). Are both the machine's identically specced? (i.e. hardware differences could account for it perhaps)
Are both build versions of IE7 the same? (i.e. it could be a bug in a particular version of IE7)