Dave,
Thanks for looking at this, I continued working on the problem myself.
FYI - I was using the insert hyperlink.
It turns out that the problem is not with Excel but with the document
management system in use here (Sharepoint). When I check the document out
and try to use a hyperlink the problem occurs, if I don't check the document
out the hyperlink process works fine.
I just have to retrofit the changes back into the DMS for everyone to use.
Thanks again, hope the explanation helps you in future as well.
Kind Regards
Alan