Paypal Express takes me to Paypal Standard

Hi,

I have my site set up with Paypal Express Check Out. Tested and tried and worked. A couple of days ago I went to place a test order on a new product and noticed that I was now taken to the Paypal Standard facility, i.e the one where you can't pay directly using a credit card without being logged into Paypal. I haven't changed any paypal settings nor any settings for the pp_express module.

Can someone give a pointer in the right direction please. A bit of a head scratcher this one, as it was working as intended, and now seems to go to the wrong paypal front-end (which incidentally is working - it's just not Paypal Express).

Any help is much appreciated!

OC 2.0.3.1

Gentle bump. Any clues? Any help is much appreciated!