I had Gabriel Knight Sins of the Fathers already installed on my PC, after I installed Gog Galaxy. I imported the folder and after the download the game doesn't start anymore. I let the client verify the files and it told me everything is fine. What now? Befor I imported it to Gog Galaxy it was running fine!

I'm having the same issue on a Mac client. When I did the automatic scan in my Applications folder, Galaxy found what it labelled as "Gabriel Knight 1." Clicking on that on the sidebar immediately crashes the client. I went to Library --> Gabriel Knight Anniversary Edition (etc.) --> more --> manage... --> import folder, and pinpointed Galaxy to the actual subfolder. This added the game, and it works now, but the faulty "Gabriel Knight 1" entry is still also there and crashes the client every time :(

I fixed my problem, too. I deleted everything and installed it new. Now it's running. I don't know what happened the first time. Thank you for the answer!

I had this issue with almost every game that used Dropbox. I could test the game by launching the Graphic Mode Setup. If that didn't launch then I ran the Verify/Repair option. That fixed every issue I had.