I've downloaded this using the GoG downloader, and it downloads fine, but when clicking "Install", the Integrity check freezes (for hours, I let it sit) right underneath the P.

My computer actually completely locks up and I need to shut it off to continue. Now, when I skip the check, it starts to install fine, but crashes at the same point (3 times now)

The attached file is the picture of where is fails.

Also, I cant find the downloaded files ANYWHERE in my computer. Program files, downloads, ETC.. Please help?

I'm getting kind of mad because I doubt this would have happened through a torrent and I really felt like I needed to support the developer for this game. What the hell is going on?

The installer tells you that there is a CRC error in one of the downloaded files, that means that somewhere between GoG and you computer something caused the file to change, creating this error.

If that's the only error message you get, you can try to download one of the 5 files based on how far into the installation you get the error. (Guessing from the timestamps in my install folder, it's the second last, or last file).

If you have a good internet connection, just redownload the 2 last files.
(setup_the_witcher_enchanced_edition-[4&5].bin)

If you on the other hand has a slow internet connection, you want to consider getting Process Explorer to see what file the installer is reading from when it finds the error. And only redownload that file. If you'd rather use the command line interface (CLI) there is a link to "Handle" (Related Links bottom right) on the page.

I downloaded the game (no GoG downloader) today, and it installed without any problems.

Good luck.