Error when opening an iso file

Hey, iv downloaded a game called Unreal 3.
Iv extracted the ISO and then opened it, then extracted that, when i try to run Mostly any file i get this error message:
This installation package could not be opened.
Contact the application vendor to verify that this is a
valid windows installer package.
does anyone know what this means? is it a corrupt download?
All the files together add up to 6gb, it would Realy suck if it didnt work.
Answer #1
Try mounting the ISO file with Daemon Tools mate. See if the Autorun kicks in and installs Unreal3. Good luck mate ^_^
Answer #2
thanks for your help man.. It seems iv made it work another way :\ i mounted the file, opened that, (got an error) then while in the program i clicked the game folder and it worked.
.. Maybe for next time, ill get daemon.. everyone always suggests to use it.
Answer #3
Iv extracted the ISO and then opened it, then extracted that
A little tip mate:
I dunno what you used to extract the ISO but I use Power ISO for all image file extractions and it’s never failed me yet. I used to use Winrar but found that on occasions some of the file names got truncated and the software wouldn’t install.