Roberttitus: I wasn't wrong. I kept downloading the same damn files until they finally decided to work. In other words... the files were getting corrupted at some point during the (lengthy) download & only through diligence was I even able to get to play the game in the first place.
I'm wondering... do you have trouble getting large downloads to work from ANY site, or was it only from GOG? Because I used to have a similar problem on my old computer, and later found out that large files I tried to download from ANYWHERE were getting corrupted 9 times out of 10. I don't usually download large files from anywhere but GOG so at first I thought it was a problem with GOG. Turned out it was a problem with my RAM. My computer worked fine so I had no idea, but it caused large downloads to get corrupted, and unpacking or unzipping large files to fail. That was the only sign of any problem, it was really weird.. but sure enough, testing my RAM revealed that it was failing (either that or my motherboard was failing). I could eventually get downloads or unzips to work by repeating them over and over and getting lucky, but most of the time they would fail.
I hope that isn't your problem! I have since built a new computer, and all my downloads from GOG, including Psychonauts, worked the first time, no repeats required. I can understand your frustration but I don't think the problem is with GOG's files.