Hi - I have been testing SS 2.4
The install is working fine on my local Windows server
(MySQL version 5.0.45 | Apache version 2.2.8 | PHP version 5.2.5)
I can see the Image Upload Iframe views fine (e.g Attach Image from your Computer or From the File Store)

However on my host server on Linux
(MySQL version 5.0.90 | Apache version 2.2.15 | PHP version 5.2.13)

I am getting an Image Upload Iframe error on all images tab views Message is "The requested page could not be found."
Iframe src ="admin/EditForm/field/MainPhoto/iframe"
So its the the absolute URL is not getting added to the start of the src

The Files and Images section has an image upload which is working as there are absolute urls on the iframe src

I have seen this issues has popped up before on this post http://www.silverstripe.org/archive/show/39366#post39366
I have tried replacing my .htaccess file as suggested

Original rewrite rule: RewriteRule .* sapphire/main.php?url=%1&%{QUERY_STRING} [ L ]

Which i replaced with RewriteRule ^(.*)$ sapphire/main.php?url=$1 [ L,QSA ]

But this causes a 500 error on the server
Any suggestions to resolve?