Picked up a disc copy of the Witcher Enhanced Edition yesterday and installed it but didn't play it, came home today and decided to try the game out but I get a popup message saying "Please Insert Original DVD of THE WITCHER ENCHANCED", I know there's something going on that isn't right because the original disc is in there and it works fine.

I looked online and couldn't find any real clue how to fix the thing and I was hoping someone here had dealt with this in the past and would know how to fix it.

Patch the game to http://witcher.wikia.com/wiki/1.5_patch, which will remove the disc check (and all DRM associated with the game). Make sure the game is updated to version 1.4 before you apply the patch, as the 1.5 patch isn't cumulative.

So that's the solution? Thanks for answering this, I had the same issue as the OP. I even returned my disk for an equal replacement and it was still the same.

Also, GOG offers a free backup of Witcher/Witcher 2 if you type your product key there http://www.gog.com/witcher/backup

All that "free backup" meaning that you literally get full-fledged, DRM-free copy of this game with a ton of goodies (artbooks, soundtracks, making-of videos and more).

The disc version of The Witcher used TAGES for a disc check, which could be a bit... finicky. Under Win Vista and later problems could often show up due to driver emulation software, or just certain types of drivers. Fortunately CDP have been quite good about supporting their games after release, and the removal of the DRM from The Witcher was part of that (and digital versions didn't include any DRM to begin with).