I have just managed to narrow down the problem and find a workaround, but I haven't found a solution.
It is opening fine locally in Acrobat 9 and Reader 7, but it is coming up with the error in Citrix Reader 7.
Just been able to get it opened in Citrix Reader 8 (same infrastructure, different icon) and I am not recieving an error message.
So this is either a compatibility issue with Reader 7 on Citrix, or a problem with the configuration of Reader 7 on our Citrix infrastructure.
I'm not sure how to progress this here at the moment as there is a call in to upgrade the Reader version distributed to all users anyway.
Hope this helps you too Scott,
Tom