Embedded Timeline on Firefox 3.5

[TechSolutions3]

The Twitter embedded timeline widget isn’t displayed on my site when viewing from Firefox 3.5.

I get the following error in the browser console:

uncaught exception: [Exception… “Not enough arguments” nsresult: “0x80570001 (NS_ERROR_XPC_NOT_ENOUGH_ARGS)” location: “JS frame :: http://platform.twitter.com/widgets.js :: z :: line 28” data: no]

[serpenostrana]

There is the same problem with Firefox 4.0 embedding the widget code into a simple blank html-page like this:
"

WIDGET CODE INSERTED HERE "

A few months ago, the same widget code worked correctly.
What’s happens?

[niall]