Greetings all. I'm having an issue running the game. I start the game, DOSbox opens, I get a few seconds of black screen (nothing else) then I am returned to my desktop. Any suggestions from fellow graduates of the Famous Adventurer's Correspondence School?

Did you try running the program as adminisrator? (Right click the shortcut)

If that doesn't work, you can also play the games using ScummVM: www.scummvm.org

I run every game as an admin, I've learned my lesson. I'll try ScummVM and see what happens. Thanks.

Tried running the Graphics Mode setup and selecting another renderer? Tried running the game in windowed mode instead of fullscreen? See if any of these help.

No change. Seems I'm destined to not be able to play the best game in the series......

You mean that even if you start it in windowed mode it will not start? Hm, time for the long debugging process then. I know QFG4 works, since I finished it yesterday, so let's try this one next.
Go to the Quest for Glory 4 directory (probably C:\Program Files (x86)\GOG.com\Quest for Glory Series\Quest for Glory 4) and edit (as administrator) the dosboxQG4.conf file. At the very end it should have the following
cls
exit
cls is Clear Last Screen, and exit tells dosbox to exit itself. Remove those two lines, so any error after Sierra.exe will be visible. You will also need to modify the game's shortcut to remove the "exit" part from the target line.
As is, the "Quest for Glory 4" shortcut should have a target line that reads something similar to this
"C:\Program Files (x86)\GOG.com\Quest for Glory Pack\DOSBOX\DOSBox.exe" -conf dosboxQG4.conf -noconsole -c "exit"
Modify it so it reads
"C:\Program Files (x86)\GOG.com\Quest for Glory Pack\DOSBOX\DOSBox.exe" -conf dosboxQG4.conf -noconsole -c
These 2 changes should prevent dosbox from closing once the program it tries to run finishes (or fails), so you can see what the error message is.
And by the way, you are using the shortcuts to run the games, right?

The error says it can't find SIERRA.ERR. Upon investigating this, it's an accurate statement. There is no SIERRA.ERR.

Perhaps another re-install is in order.

Interestingly enough, adding that file seems to have fixed the problem. Many many thanks.

No worries, enjoy the lovely Mordavian Nights

Is there a similar fix for QfG 5? When I launch the game, I get a black screen and an error message. I tried re-downloading and re-installing, I tried ScummVM, and I even tried de-bugging it using the advice JMich gave for QfG 4, but there is no dosboxQG5.conf file.
I have had no issue with any of the other QfG games. Does anybody have advice?