Also, Netflix has been working on Chrome, Facebook runs fine too.

I have the same problem as both of you, on my desktop computer running under Windows 7.

Somewhere in this or some other Firefox forum is a discussion of the same problem when running in Apple's OS.

Presumably the user's Apple was 64-bit, because the official advice was to set Firefox to run as 32-bit. But the procedure for doing that doesn't work in Windows 7. Can it be done, and if so, how? Where do I go to change that setting?

Alternatively, why are Apple and Windows users alike suddenly getting this odd behavior? In my case, Netflix (which plays fine in IE and Chrome) just quit working, but all other streaming media continue to work. Maybe Firefox did an automatic update, and the update changed something vital?

Not kvetching, mind you, just trying to broaden the scope of the question.

For Windows, Firefox is a 32-bit application that only runs in 32-bit mode.

Can you check that Silverlight is both enabled and allowed? Here's what I mean:

(1) Check the Add-ons page to make sure Silverlight is enabled. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Then, make sure Silverlight is not set to "Never Activate".

(2) On Netflix, on a page where you expect Silverlight to work, check the site's permissions. You should see a plugin notification icon in the address bar (looks like a small Lego block). If you click that, is Silverlight already approved or do you need to approve it?

More generally:

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

"3-bar" menu button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click and choose View Page Info > Security > "View Cookies"
• Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page (and you will need to login again). Does that help?

That did the trick!

Silverlight was set to "Ask to Activate." I don't remember ever being asked to activate it, but I set it to "Always Activate" and that seems to have made the difference. At any rate, Netflix plays fine now.

I'm pretty sure I never set Silverlight to anything myself. I wonder how the setting changed, or if it didn't, why "Ask to Activate" no longer worked. No matter. It's all magic anyhow. All you need is the right incantation.

Thank you so much for being so prompt and thorough with your instructions. I cannot recall when last I got such splendid support from anyone.