thanks whitelamp
it sounds very much like it is the same issue but I dont know that i feel technically skilled enough myself to fix it.
the other thing is that i have received just one report about it from one customer and i havent been able to replicate the same behaviour myself so it is hard to know whether it was a one off or if it has been fixed?
I also wondered whether the fact that they were accessing the site via an affiliate link – i am using the affiliates pro plug in- was complicating matters even more?
any thought or help you are able to offer very much appreciated.