I apologize for not perhaps not giving enough information. The computer is a Compaq SR 2010 NX, 120 GB HD,that belongs to a friend that is disabled. He asked me to check it out as it was running so slowly. I installed a 1 GB of memory, ran CCleaner, defragged the HD and Registry, and the machine, other than the Firefox problem performs almost as good as new now.
After the first failed attempt in opening Firefox 3.6.6 after installation, he told me that someone (?) had tried to install Firefox and it would not open for him either.
I have not tried the Safe Mode installation as it may be a few days before I can get to it. My research with Firefox and others on the net that have had the same problem have said that the Safe Mode install doesn't work either.
I am about ready to install Chrome on his machine, and then wait until the bugs are out of the new Beta Version of Firefox, and try it again. (Anything to get away from IE8)
I do appreciate any help. If I do find a solution to this problem I will post it here.