I'm not sure whether your problem is connecting to the remote computer, or using Firefox on the remote computer.

Connecting: you may want to use the new plug-in.

Check

Tools > Add-ons > Plugins

if you have a version of the LogMeIn components older than March 2011 (more info link), then try logging in here instead of the usual LogMeIn page:

http://beta.logmein.com/

This should offer to update your plugin. (If that doesn't work, you might need to remove the old plugin first and then try again.)

Using: I can't think of any reason that you wouldn't be able to use Firefox on the remote computer.

I can connect, I just cant use the browser or any controls of the browser, when using Firefox. (As if all access thru LOGMEIN is being blocked) for Firefox ONLY. All other programs work fine, including internet explorer. This ONLY happened since upgrading to Firefox 4.0.1

Is it 4.0.1 on both PCs (local and remote)? I will try to replicate the problem later.

Both the remote and local PC are using Firefox 4.0.1

I'm posting this from my office PC, controlled by my personal laptop through LogMeIn Free, with Firefox 4.0.1 on both ends. So it should work.

It's hard to think of any reason for yours not to work. This article is a very comprehensive approach to troubleshooting Firefox problems, but hopefully someone will be able to offer more specific suggestions as well:

http://kb.mozillazine.org/Standard_diagnostic_-_Firefox

Fixed it....It was the Adblocker plus stopping Logmein. Once disabled in firefox safe mode, everything worked fine.