When I start the game, all the opening cutscenes play, but when I load my save file, it just closes and returns me to my desktop. I don't know how to fix this.

Unfortunately there's a bunch of possible reasons. Let's try first if your savegame is corrupt.

Download this save:

http://www.mediafire.com/file/g3wggmxearti80j/000376_-_Triss%2527_Haus-376.TheWitcherSave/file

If you don't know where you can find your saves then use the explorer and seek for

*.thewitchersave

Can you load the save?

Sure. After three days without feedback I assumed that your problem wasn't an urgent one and moved the savegame to trash. Meanwhile I restored it. Try again.

Sorry, I got it to work. Thanks