While you're waiting on someone better qualified, have you read this? https://github.com/dadler/thumbnail-zoom/issues/166 I'm not sure the issue even gets resolved there but it does seem to point to your "Thumbnail Zoom Plus" extension. A corrupt Firefox profile? A conflict with another extension? Personally, I'd be tempted to disable all extensions except "Thumbnail Zoom Plus", see if the freezing goes away. If it did, I'd enable the other extensions one by one, testing along the way. On the other hand, If disabling all extensions except "Thumbnail Zoom Plus" didn't cause the freezes to go away, I'd maybe reset Firefox. If resetting didn't resolve the issue, I'd remove Firefox completely, including my profile, and reinstall it. I'm not a technician though, just saying what I might do. BTW, I just added Thumbnail Zoom Plus 3.1 to Firefox 32.0.3 to test and other than being a bit picky about how I move my mouse in to hover, it worked okay. Meaning no freezes or script errors. I'm on Linux though. If I were on Windows, I might consider the possibility of a conflict with my AV. Someone else could tell you whether or not that's a likelihood though. Opps, I's so slow I see Mikie already gave you good advice. I'll go ahead and submit it though... just in case something helps, say in the bug report I linked too.

Is he using an email client (Outlook Express maybe?) or is he using Yahoo webmail? If he is using an email client, has he tried the webmail?

These are the exact instructions that I copied from that site: Open Internet Explorer. On the Tools menu, click Internet Options. On the Security tab, click Internet. Click Custom Level. (Fig.1) Scroll down to Active scripting. ****Click Enable (or Prompt). (Fig.2) Click OK. Click Yes. Click OK Just tried it and it didn't work for me. When I got to where I was supposed to click "enable active scripting or prompt" (see above asterisks in above instructions), I saw that my laptop was already set on Enable". So, I clicked on "Prompt", finished the directions, closed and then reopened . . . to a nightmare of boxes that continually popped up asking me if I really wanted to do something. I unfortunately can't remember what it was now, but no matter whether I clicked on "yes" or "no", they continued to pop up. I had to shut down the computer, then get back on, go all the way back to that place in the instructions, click off "prompt" and click on "enable" once again. Turned off the computer, turned it back on again . . . and now I'm back to the script error PIA. I am so frustrated!

WOO-HOO!!!! Thanks Firefox AND Forboystoo!!!!!!!!! The YesScript worked for me!!! I couldn't the Icon when I was first looking in the window that pops-up when clicking "Customize". Had to close Firefox a couple times, then it finally appeared! Soooo...dragged it up to near my "Home" Icon. As stated, you can toggle it "On & Off" when you're in a site. On mine, I get no dropdown window from the Icon, like some screenshots show. If I hover the mouse-arrow on the darkened Icon though, a little balloon appears, stating "gardenweb.com-blacklisted". Is the drop-down window from YesScript an option?! Faron