I'm left with another error message though. I get it if I am in Orders screen, the go into an order and then press Back. I get

There was a problem retrieving transaction details. (Field format error: ORIGID missing)

This is ONLY on order which were made before I implemented Website Payment Pro and doesn't seem to cause any problems to me.

Paypal have said:
It seems that you are not passing back the original transaction when submitting an Inquiry transaction. You would need to Set ORIGID to the PNREF (Transaction ID in PayPal Manager reports) value returned for the
original transaction.

Could the wonderful Zen-cart communitiy offer me any guidance?

Regards
Natty