Hmm, sounds like some JavaScript functions are disabled, very selectively.

Could you try minimizing your active add-ons? In particular, set nonessential plugins to "Never Activate" and disable any nonessential or unrecognized extensions. Either:

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

In the left column, click Plugins. You might start by setting everything other than Shockwave Flash and Silverlight to "Never Activate". You can come back and allow some other plugins as needed.

In the left column, click Extensions. I don't see any issue here at the moment, based on your system information.

You might need to exit and restart Firefox to see the results of these changes. Any improvement?

So I disabled everything other than Flash and Silverlight in my Plugins but after restarting firefox there was no change.

Can you think of any software changes that might have occurred outside of Firefox, with Windows, or your security software, or your router, or anything else?

Some general thoughts:

(1) You could check the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the additions by date to see whether there is anything recent there.

(2) You can check your Firefox connection setting here:

"3-bar" menu button (or Tools menu) > Options > Advanced > Network mini-tab > "Settings" button

The default setting of "Use system proxy settings" should piggyback on your Windows/IE "LAN" settings, but you also can try "No proxy" to see whether that helps.

Well, thanks to your instructions here i've come back with some good news. everything except for the load more button on youtube is working after I clicked the No proxy button, not sure what to do about the load more button on youtube though

In case Firefox is using a messed up cached version of one or more YouTube files obtained with the previous setting, could you try:

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"
• (menu bar) Tools > Page Info > Security > "View Cookies"

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

Then try reloading the page. Does that help?

It did indeed. Thanks a lot, you were a great help!