Thanks, Dr Byte. I've uploaded the 1.3.9h paypal files again as it seems a few of them were the wrong version. I've also done a test sale and it went through fine (although this doesn't mean that live sales will go through any better as I can't replicate the problem).

Is there anything else you or anyone can see with the information I've given here that could cause issues? Database for example? Just wanna make sure I've asked all I can.

I'll be getting a whole load of live sales from March 30th 2012 so it'd be great if this thread could be kept open for a little while. I'll post back early-mid March and let you know if the problem is solved.

Thanks again,

Tony