Was just trying out the CD version of "Space Quest IV" and just noticed a problem I haven't seen listed on the bug tracker (unless I missed it). At the very first screen of the playable portion of the game (right after Roger lands in "Space Quest XII"), I was unable to walk onto the screen immediately north of the starting screen. Roger walks onto the screen and immediately turns around and returns to the previous screen.
Also, just to make sure it wasn't the game itself, I tried it in DOSBox and did not have this problem.
Duplicate of bug #3092223. It's a script (timer related) bug. Closing, and adding it to the known SCI bugs wiki page