I recently upgraded to the latest version of DOSbox from the previous build. At the same time, I also got D-FENDv2

Since then, lots of games that used to work have ceased to do so, including The Elder Scrolls: Arena, Eric the Unready and Superhero League of Hoboken.

Anyone else found that things stop working? I'm told that the newer version of DOSbox is a huge improvement when it comes to playing games, but so far I haven't been able to get far enough to tell in most of them.

Tried withoud D-Fend already?

These problems only has been noted with people using D-Fend.
Try without it and it should work.

AHA, I seem to have solved it!

The new version of D-FEND defaults to putting hercules as the default graphics card type for each new profile. Changing this to vga makes all the affected games (so far) work again!