Starting from the daily build of 2 days ago WebGL stopped working for me.
The call
canvas.getContext("experimental-webgl")
throws an exception:
[Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIDOMHTMLCanvasElement.getContext]" nsresult: "0x80004005 (NS_ERROR_FAILURE)"

This happens both for my code and for any example and tutorial out there (for instance the ones in learningwebgl.com.
The only change that occurred was that firefox restarted to apply the update and then it stopped working.
webgl.disabled in about:config is false

Chrome 9 still works perfectly.
I restarted firefox a number of times and even restarted the machine.
Any idea what's going on?