Why the difference?
If I click on 'browse server' I can upload a doc (and presumably other formats too) from there, but if I click the upload tab then 'send to server' after selecting a file, I get the error message. However, if I choose the latter route for uploading an Image or Flash movie, I don't get any error. Seems inconsistent and likely to confuse the end user.
Having managed to upload a file, I now get the error when I try to update the page.
Warning: Cannot modify header information - headers already sent by (output started at /home/...../public_html/adminsection/admin/pagesform3.php:4) in /home/...../public_html/adminsection/admin/pagesform3.php on line 58
which I didn't receive yesterday!