So I bought Ultimate Doom, and started it downloading a few days ago. (also downloaded Arena and Daggerfall, which came with it)
No problems downloading them.

This evening I finally have some time to load it up and play for a bit. No dice.

A console window opens, then the DosBox window splashscreen opens, and then they both close/crash automatically.
This happens when trying to launch the game from my Gog Galaxy client.
First reaction was to use Gog Galaxy to verify game files, and then uninstall and reinstall. Still no change.
I went to the install directory and tried running DOOM.exe, and then recieved the attached error pop-up message. This seems odd to me, because I've never really had any problem with DosBox games from GOG on this system.
I try to change the compatibility modes. Nothing.
I run as administrator. Nothing.

I try all of the above on Arena, same behavior. Daggerfall, same same...

I did some googling for a few minutes and didn't find anything relevant. I searched GOG's support and community forums, found nothing.
I haven't tried installing on another machine as of yet, because I don't have convenient access to them at the moment.


Anyone have any other ideas? I'm open to suggestions...

Thanks for the reply.
I only tried running the exe directly after the desktop shortcut and GoG Galaxy client immediately crashed.

Your suggestion of the Start Menu shortcut seemed like something to try, but I just discovered that there are such shortcuts for all my other Gog games but none whatsoever for Doom, Arena, or Daggerfall. (none added to the desktop either, even though I checked that box during installation...)
I uninstalled and reinstalled via the Galaxy client, still no Start Menu shortcuts. Same behavior as before. I downloaded the backup installers via the Galaxy client, and the same results.

I downloaded the installer directly from my Gog Library website and the installer threw an error this time. I attached an image of the error popup. I'm unsure what 'temporary' files it is trying to access? There was one setup file that was downloaded. What else does that setup file need to run?

The only thing that has changed on my system is I recently switched to using Avast as an Antivirus, is there some kind of conflict here?

Well now I just feel silly...
This was it exactly. :-P

I temporarily disabled the 'realtime protection' and bam, everything installs like normal. (I would have expected to see some kind of notification that there was a problem with the installation from the Gog Client.)

Be careful if your AV suite intermittently auto scans your system, or you'll be digging the files it has flagged out of quarantine. If this occurs, you will have to make those files exceptions for your AV software so it leaves them alone. So, if you attempt to play sometime soon and the problems are back, I'd check this first.