I don't have any CD-ROM drive configured in DOSBox when I run the game, but I suppose that the page fault could still happen for that reason, if it is a CD check, after all. CD checks that don't actually tell you that they're CD checks--they just leave you guessing at what the problem is--are nasty.
liqmat, no. It happens within the first 30 seconds of playing and, if you're playing in 640x480, usually before you even get into the mission. If you're mounting the game's ISO in DOSBox, though, and the game really is looking for free space on the CD, you're probably satisfying the check, so you're avoiding the issue.
ripsaw, do you have any idea why the main menu buttons often don't work after launching the game and why a simple right-mouse-button click fixes it? I imagine that I'm not the only person that this happens for, since it happens with every DOSBox build and setting that I've tried (including autolock true and false). It's really simple to workaround once you know how, but I can imagine how frustrating it is for others who haven't figured it out yet.
EDIT: Ah. The mouse bug happens only when dismissing the Bethesda logo vid with the left mouse button, not when dismissing it with the spacebar. I wonder if the game is handling the mouse button down event, but not the up event, so it's not ready for a new left click when the menu appears and it takes a right click to reset it.