Please check that you have the P7zip dependency installed.
7z x -tiso /media/SOFTWARE/ISO/Operating Systems/pclinuxos-kde-2011.09.iso -o/media/PCLOS_USB_STICK.3354/tmp
It seems the error may be because of the path not being acceptable .... try changing the folder name from/Operating Systems/
to see if that cures the problem.
It appears that this command does not have the path escaped/quoted so the space may cause an error.
If this is the problem then it will need to be corrected in an update.
Thanks for the full output .... appreciated.
Yes it appears it is the space that is the problem ..... from the man page ....
Wildcards or filenames with spaces must be quoted:
So in the case above the path needs to be quoted because of the space.
Thanks for bringing this to my attention.