HELP, I have the game on dvd-rom, it said to just use disc 1, and while installing "installation cannot proceed without the required file, do you wish to cancel?" pops up, and when I click no the file folder opens up but anything I click on in there, nothing happens. Did I miss something? Any help would be appreciated as I'm desperate to play this game. cheers folks

You could try this:

Installation failed with code -10: File reading error

Solution

RETAIL (PHYSICAL DISC) COPIES:This kind of error happens when your disc drive cannot read the file on the disc. To fix this, please:
a) copy all the installer files from all the discs onto your hard drive, and install from there, or
b) use the code printed on the back of your booklet, to redeem the game on GOG.com, here: www.gog.com/redeem/

GOG.COM DIGITAL INSTALLER VERSIONS
Make sure that you have at least 30 GB of space available on drive C:, or that you do not install the game onto drive C:. Otherwise you might run out of space during the installation, and it will fail.

If you have to download all files (point b): Account - Library - Witcher 3 - left side of the "pop-up" (7 files, 1 exe-file and 6 bin-files) - download all and install later by double clicking the exe-file.

Don't forget to download the latest patch (2 parts): A lot of bug fixes and improvements and you need it if you want to install all the free DLCs (at least for the newer ones).