Here's a tip that worked for me. This is on Windows 10 64 bit but may well work for other OS's. I was having trouble with Dungeon Siege 1 crashing seemingly randomly. I had tried the solutions that GOG suggested but they didn't eliminate all of the crashes. Then I remembered a fix for another old game - Neverwinter Nights. So I tried it and it seems to have worked. I have not had any crashes since. The thing is this is only for those using NVIDIA graphics cards. So here is what you need to do.

Open the NVIDIA Control Panel (Not the Experience)
Under 3D settings select Manage 3D Settings
In the right-hand panel select the Program Settings tab
Once it has finished populating the list open the drop-down list under where it says "Select a program to customise:"
Scroll down until you reach Dungeon Siege and select it
This will populate the large box under where it says "Specify the settings for this program"
In this box scroll all the way down to the bottom
Almost at the bottom you will see a setting called "Threaded Optimisation"
Set this to off

and that's it.

The reason this appears to work is that DS1 was made before multi core, multi threaded CPUs were commonplace and so can only handle single threaded working.

Hope this is useful.

TR

There is a command line that seems to be useful for NVIDia Crashes. Historically it solved crashes to desktop and unstability under those cards

bltonly=False

Probably the wrapper in game was specally added for avoid that kind of crashes in some cards and make it more stable.