Orange ZTE MF636 Dongle won't install on Macbook Pro

I have used my orange dongle on my macbook pro for over a year now. All of a sudden it stopped working, I got a new one sent out, same problem.

So i got out my old mac, it works on here no problem.

WHy has it stopped working? When i try to install it again on my MBP i get one of two messages.

'The installer can't create the folder "var/folders/ET/ETdH4oGzF2CiKTotoAWDXE+++TM/-Tmp//Install.13400mjsPY".

Or ' The installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance'

I have tried installing direct off the dongle and downloading the driver from orange themselves.

Can anyone help?

Thanks

Jon

ANYBODY?

Thought we had some experts here?