Are you sure you mounted the correct Program Files directory? 64-bit windows has "Program Files" to store 64-bit apps and "Program Files (x86)" to store 32-bit apps, but a 32-bit app will see "Program Files (x86)" as "Program Files" instead.
Can you see the Sierra directory when you run dir inside DOSBox?

No I can't see it when I run dir. The mount worked without a problem and you can verify accuracy on the wikipedia. You can't designate a directory name with whitespace in DOS, you can in Windows.

DOSBox is not DOS. It accepts spaces if quotes are used, e.g. "c:\Program Files". But if you want to insist doing things the "DOS" way maybe try mounting progra~2 instead of progra~1 because I'm pretty sure you've mounted the wrong Program Files directory.

Don't mount a systems folder or you will likely encounter permissions issues. This is why GOG started to install old games into a folder like "c:/GOG Games" Create a new base folder named something like "Old Games" and mount that as you C: drive

I had to reinstall the Space Quest Collection under a different directory, C:\SpaceQuestCollection rather than C:\Program Files (x86). I am surprised that DOSBox does run those games.

Also, when I exited the game DOSBox had grabbed my mouse pointer so I had to use Ctrl+Alt+Del to bring up task manager and I stopped DOSBox from there.

Depending on the version you are talking about, DOS also accepts spaces if quotes are used. MS-DOS 7.x supports long file names, and quotes are required if there are spaces in the file names (quotes are optional otherwise).

Ctrl-F10 releases/captures the mouse pointer.
Ctrl-F9 will close DOSBox.

If you are talking about the 2006 VU SQ collection, try the new installer. It will restore all of the missing files and optimally configure the games. Also you can use the latest DOSBox. The DOSBox that the original installer uses is the very old 0.65.

http://sierrahelp.com/Patches-Updates/NewSier … tml#Collections