Which page are you trying to reload?
The main page or the page that you opened in a new tab?

Does it work if you press F5? Reloading a page by a click on the Reload icon on the right end of the location bar should work and you should see a (short) change from the Reload icon to the Stop icon.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See:

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

I'm talking about refreshing the new tab opened via the scroll wheel or via the New Tab button. The refresh button works fine on the original page.

F5 doesn't work either.

I no longer know how to open Firefox in safe mode. There used to be a selection for that in the Start Menu. With Firefox 4 that selection no longer exists. I guess I'm going to have to search the web to find out how to do that. I becoming a little concerned about version 4.

You can use "Firefox > Help > Restart with Add-ons Disabled" or press the shift key while you click the Firefox desktop shortcut to start Firefox 4 in Safe mode.

Thanks. I found that the safe mode trick. It's a little difficult to find things now after using Firefox, Mozilla, and Netscape for eons. :-)

It was a plug-in: McAfee's SiteAdvisor 3.3.1. That's too bad because it was very useful and part of my McAfee security package, but the refresh button works normally without it.

Thanks.

McAfee SiteAdvisor disabled. Problem solved.

Thanks Gene. Good job. I did the same thing and refresh works again !

Now we have to rewrite this problem:

Firefox 4.0 (and at least 1 previous version) is no longer compatible with McAfee SiteAdvisor (which I, for one, would like to continue to use !)

According to McAfee's forum, they know about the problem and they're working on it. Knowing McAfee, it won't be tomorrow. haha.

Thanks for posting this question (and answer), Gene! I was having the same issues. Too bad about Site Advisor. It's a great little utility, however given the choice between disabling the McAfee add-on and switching back to nefarious, Binged-up IE8, afraid there's no choice but to disable Site Advisor.  :(

Thanks again for the helpful post!

I had the same loss of back/forward button function come up shortly after updating to 4.0.......Checking add-ons, there was nothing for McAfee. However the B/F button function did return after disabling the dictionary.com toolbar add-on.

Coincidence you be the judge.

I don't use any toolbars, but I think there are probably more than 1 or 2 add-ons that are incompatible with FF4. Apparently you've found another one.