Thanks for the reply. I've changed the website structure and created a sub-domain which points at the same folder and the picture urls are now created correctly. I am, however, experiencing another problem with inserting pictures using tinyzenpage. I cannot get the custom thumb left working - it was working initially, but after several goes experimenting with the CSS formatting etc, all pictures now float right. I've used different browsers (firefox, IE and chrome) but still the same.
If I can get this working, then it's looking excellent.
Thanks for your assistance.