I have tried to download and run Firefox on my MAC OS 10.6.7 several times and have run into this error message every time: "A copy of Firefox is already open. Only one copy of Firefox can be open at a time". A search through the computer does not fine another copy of Firefox and there is no window open or evidence of the program open. When I got this computer a year ago I copied the hard drive from the old computer onto the new and the old computer had a copy of Firefox on it and the program worked on that computer. It would not run on the new computer so I thought maybe it was due to the Intel chip so I deleted the program and downloaded the newest version at the time. This is when I started getting the error message and subsequent attempts have yielded the same results. Can you be of help?