Web-Content does not appear HTTP

Hi,

Have you already got problem of content or image that do not appear ?

We have a terrible problem on all our WS :
1. Some images does show up on web pages (15 % of time).

2. Content does not appear (15% of time)

3. Placing http://www.exaland.com/z-extras/test.htm
under a browser Home Page, and launching processes of this browser, we
see the problem of images or content that does not show up !!

tested from diferent computers and ISP.
Server is UNIX/FEDORA/LINUX/PHP. Hosting problem ? Server.conf problem
?

Many thanks for your help.

Anne