Do you have that problem when running in the Firefox SafeMode?
http://support.mozilla.com/en-US/kb/Safe+Mode
Don't select anything right now, just use "Continue in SafeMode."

If not, see this:
http://support.mozilla.com/en-US/kb/troubleshooting+extensions+and+theme...

That worked fine - thank you. Does that mean that I shall have to use Safe Mode every time I need to access this website?

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Seems to be working now! Fingers crossed then. Many thanks.

No need to use Safe Mode. No need to turn off all extensions.

I traced the problem it directly to AdBlock Plus extension. I disabled blocking for weebly.com and my website.

Upon refresh, my widgets (in Custom HTML elements) showed up in my Weebly Editor and on the published site.

My problem turned out to be the AOL toolbar. I disabled that, upgraded to Firefox 4 and no more problems. Although I wish that all open windows stayed open after shut down and reboot.