Looks like you might have a corrupted installation. Please make sure you have auto updates enabled. This will ensure you have the most recent version of DH.
Try the following steps in the order listed until the problem is resolved:
1. Use Steam's
intregrity check tool
2. Go to the System folder in your DarkestHour directory. Find the file named DarkestHour.ini and delete it. Restart the game through Steam. Be aware that some of your game settings may change due to the deletion. You'll need to set those up again.
3. If these do not work, uninstall Darkest Hour and reinstall through Steam.
In regards to your Jackboot Games forum registration issues, please send me a PM here with the following information, and I'll get you set up:
Desired username and the assortment of email addresses you attempted.