Thanks Octal. Now on my laptop. I deleted the profile folder but then Firefox wouldn't start saying that a process was still running although it wasn't listed in task manager.
I rebooted and it still wouldn't run even after I re-installed it. I then tried a system restore and it wouldn't start at all, nothing in Task Manager either. I reinstalled it again and it tells me that Firefox is running already but doesn't start.
Now going to load a disk image backup and start again. Maybe this time I'll just delete the themes and extensions first.