1)Download both SINS and Entrenchment again.
2)Upgrade your video card drivers
3)Press CTRL SHIFT TAB after you get to the black screen (a shortcut to windowed mode) If this doesn't work for you let me know
4)If/When you get into the game try turning down your texture quality settings.
* And as usual, you won't be able to open pre beta mods, saved games, or replays.

Good luck!

Going to reinstall get back to you shortly.

If you had any mods loading on startup in regular Sins before you updated to Entrenchment, like me, then that's possibly your problem.

I had Bailknights graphics mod loading at startup and once entrenchment was installed I could no longer launch Sins at all.. just a blank black screen. :/ To solve it I went to my Mods folder and moved the mod's folder into another folder, and voila.. the game couldn't try to load it, and entrenchment started up just fine.