does sins lock up or just entrenchment?
what does impulse say are your installed versions of each?
should be easy enough to...at...worst...uninstall sins and entrechment completely, and then reinstall using impulse (not the cd). the reg codes should already be connected to your impulse account. once sins is installed and fully updated, then install entrenchment again.
if you are locking in both sins and entrenchment, then you have something else going on. maybe a video driver issue or something. to troubleshoot that we will need more specifics about your os and hardward.