Hi
I have read the topics on this subject, and since I am encountering the same problems, I am posting my findings.
I have a new installed computer with XP Pro+SP1. I burn a CDR with Portable Firefox along with Apache (portable configuration of it), and PHP. My application is working fine using default browser installed on my computer like normal Firefox and IE.
When I launch portable firefox from CDR either automatically or by double clicking on the EXE, I get the now well famous message: "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system." Needless to say, that I did not change an inch of the config of firefox, nor the EXE name, nothing at all. I am using what has been packaged and extracted.