Here is the answer:

I just got off the phone with McAfee Tech Support and as of a few minutes ago, McAfee Site Advisor is NOT supported on the newest versions of Firefox, IE, or Google Chrome!!

I was told if I wanted Site Advisor to work I needed to go back and reinstall and use an older version for each of Browser.

You should continue using the most modern versions of your browsers and wait for SiteAdvisor to catch up (they need to update their software to support new browsers, not the other way around). SiteAdvisor does little to protect you, but having old versions of software is far more dangerous.

Thanks Tylerdowner,

I agree completely and told McAfee just that!!

I just got a follow-up call from McAfee and Site Advisor is now working with Firefox & Google Chrome, but not in IE.... which doesn't matter to me because I NEVER use IE!!!

Firefox 26 and McAfee SiteAdvisor Enterprise

My university uses McAfee SiteAdvisor Enterprise Version number: 3.5.0.724, service pack 1on its system. I have had to stop the Site Advisor plugin repeatedly. It slowed bowsing to a crawl. It still happened 5 hours ago, but seems to have cleared subsequently? So there is hope.

I also cannot stoop to using IE.

I had the same issue for months. I found the easy way to fix it. Go to the SiteAdvisor RepairCache folder on your computer (typically C:\Program Files (x86)\McAfee\SiteAdvisor Enterprise\RepairCache), and run file called sae.msi

You may need to close the Firefox first. It will prompt you to install the SiteAdvisor, so just follow the instructions. It takes about a minute or two. When it's done, just start the Firefox again and you should not see the error anymore.