This issue is related to Internet Explorer 8.The error can be resolved by adding the IP address as a trusted site in Internet Explorer 8. 
I am connecting to a Drac 5 with firmware version 1.33 using 32-bit Firefox 2.0.0.20 as downloaded from Mozilla.org running on CentOS 5.2. I seem to have installed the Console and Media attaching plug-ins OK but I get a problem when I try to attach a DVD-ROM. I select the ISO image of Centos 5.2 but when I press the Connect button I get a pop-up stating that "The page at [URL] says:" then "Invalid CD/DVD-ROM selection.". If I try the same thing using IE 7 on Windows it connects, but since I don't have Windows at the datacentre it is too slow and no use to me to try and connect a DVD over the WAN. I searched Google and found nothing documenting this error so I am a bit stuck as to what it means and what to do about it. I have tried running firefox as root also in case the plugin was trying to loop-back the ISO file. I have also eliminated any firewall blocking ports.
Drac 5 attaching media: "Invalid CD/DVD-ROM selection."