Normal Firefox execution sets current working directory to $program_files/Mozilla Firefox when executing firefox.exe, this is required for some applications, for example, an applet using softokn3.dll to access Firefox keystore, because being this the current working directory other dlls can be found by the application.
To the time Firefox Portable current working directory is the same where FirefoxPortable.exe is which makes fail some applications that depend on normal Firefox current working directory.
What do you think?
Please take a look at