Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).
See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears.
You can use "Disable all add-ons" on the Safe mode start window to disable all extensions.
You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Thanks for your reply. Safe mode doesn't change things. This is mainly an issue in ebay. It appears to have something to do with java script so I've turned it off for now.

On some sites menus open if you hover the menu headers. This can be done via JavaScript or via CSS.

Can you post a link to pages where you see that happen?

http://shop.ebay.co.uk

this seems to be the "latest and greatest" in web design, but unfortunately it renders some pages incredibly tricky to navigate.

for example, if my mouse cursor is in point A, and I need to get to point B, I do not want to trace a circuitous path just to prevent mousing over locations between A and B that trigger hover menus (which, given Murphy's Law, inevitably cover up the point B I seek).

it has nothing to do with "safe mode" - the hover menu is an intended feature by the web designer, but it just hasn't been well thought out and leads to a frustrating experience.

it would be great to have a feature in Firefox that says "change all hover menus to activate only on click" - namely, to remap the MouseOver() Javascript event into a MouseDown(). *

• my Javascript is pretty rusty; I don't remember the exact terms, but they are something similar to that.