Hi Jorge,

I understand that you are trying to install a version of Firefox in a computer that is being accessed with multiple accounts.

There's not such thing as a multi-user version of Firefox. What is probably happening is that Firefox was installed only for one users. While I'm not really familiar with Windows anymore, in the past, whenever you decided to install a software, Windows asks you if you want to make it accessible to every user or only the person who is installing it.

I would recommend you to uninstall it and install it again. This thread from the Microsoft help forum may help you: How to change access settings for apps.

Let me know if it helps. Ibai

Mozilla hasn't released a 64-bit version for the Windows platform. The 32-bit version works fine on 64-bit Windows.

Take a look at this:
http://frontmotion.com/Firefox/index.htm

"MSI installers for Mozilla Firefox! Useful for deploying Mozilla Firefox across thousands of computers automatically with Microsoft's Active Directory. ..." 

got it thanks , what happened I was working on a master image for windows 7 64 enterprise and working with the default profiles... , I have the issue with firefox ... but I realize that it work if I don't change anything on the Default profile it will work like you said ... don't need multiuser version " don't exist " after make some changes on my default profile ... I have to leave my folder options show the hidden files , folders and it work ok . Now I configure my default profile the way that I want and its working ok . its easier on windows xp but on windows 7 64 I have to make few changes and it work . Appreciate your time to response my question and now is resolve . thanks again