Just some info that might help anyone getting frustrated over getting VirtualHost containers to work (like me )
I have several virtualhost containers setup, all working perfectly. Only one just wouldn't work and I couldn't find out why. The setup was exactly the same as the other ones, but whatever I tried I kept getting an internal database error (error 500). I searched everywhere, and tried everything, but nothing worked. I was about to post my problem here.
But then, on a hunch, I had another look at the files in my local directory and saw a .htaccess file in there with some redirects in it. Again on a hunch (I was at the stage where I was just trying everything), I temporarily deleted the .htaccess file, restarted apache, and voila: everything worked. GREAT!
So if you you also have a .htaccess file in your local development directory, and you keep getting an internal server error with your VirtualHost container, try removing the .htaccess file and see if that solves the problem.
Hope this helps anyone.