mime and nautilus

[Rob Brown-Bayliss]

Hi, I am getting the following errors on FC5, for all image types, videos,

The filename "map2.jpg" indicates that this file is of type "jpg
document". The contents of the file indicate that the file is of type
"JPEG image". If you open this file, the file might present a security
risk to your system.

And fro PDF friles I get this:

Unhandled MIME type: 'application/x-extension-pdf'


All other files (text, spreadsheets etc) work fine.

All the files that give the werror can be opened in the correct
applications by selecting the appropriate app from the right click
menu,  but it's anoying and honestly looks dumb when showing people
something,

Where would I start looking to fix this?

-- 
Rob