OK, so I had to replace my laptop's HD and reinstall everything from scratch. On my desktop PC, my impulse account correctly shows that I have the original Sins and Entrenchment. But when I sign onto the Impulse account on my "new" laptop, it shows all my games including original Sins, but not Entrenchment. I'm using the same account on both. They're both running Vista.
Any ideas? I've checked the Views mode to make sure it isn't hiding uninstalled games, but that doesn't fix the problem. On both machines, view is set to: Details-view, Fade non-installed applications, and Show information panel.