Downloaded the latest version of Firefox, I've completely lost access to Firefox and am unable to open it or even uninstall it.

Mcafee prompted me to update to the latest version of Firefox, but after it updated I've been completely unable to access Firefox. I get the error message: ---Windows cannot access the specified device, path, or file. You may not have appropriate permissions to access the item.--- I get this message when trying to uninstall it as well. Attempting to to install a new version of Firefox does not do anything. After that I tried to delete the Mozilla from Program Files and then reinstall it, but I'm told that I need permission to perform this action. After trying to take ownership of the folder and files, I received this error message: --- An error occurred while applying security information to: C:\Program Files\Mozilla Firefox\firefox.exe Failed to enumerate objects in the container. Access is denied. ---- How do I get control of Firefox, get rid of it and reinstall it? EDIT. Restarting once didn't seem to make a difference, but for some reason after my second restart, the problem seems to be resolved.