I have installed Centos 6.2(32 bit) to my linode and updated it. Installed apache,php and mysql with phpmyadmin. All working well.
Accept when I upload a png image via ftp it doesnt show on the page. I download the uploaded png and try to open it. It says unknown file type.
I used 3 different ftp programs with ascii and binary mode still no luck. Then I used wget to download the png from another server. Still png is corrupted.
Same with flash files with .swf extension.

Then I installed fedora no luck, ubuntu no luck. Still no png support. I went back to Centos.

I dont think it is an apache issue. Somehow linux corrputs the file that is uploaded.

Any suggestions to solve this appreciated....

Solved. Firstly the original png files were corrupted. Second need to set :
EnableMMAP off
EnableSendfile off

in the /etc/httpd/conf/httpd.conf file

Enabling those options should not be required, and will have a large negative performance impact for serving static content.