D-Fend mounting system makes it different from any other front end out there.
Here's how it works:
Say you have a folder where you keep your dos games (I do) called C:\DOSGAMES
In this folder is another folder named DIGGER (that's C:\DOSGAMES\DIGGER)
When you mount C:\DOSGAMES as drive C and select C:\DOSGAMES\DIGGER\DIGGER.COM as Game EXE for a profile D-Fend will do the following.
If C:\DOSGAMES is C:\ in Dosbox then C:\DOSGAMES\DIGGER is C:\DIGGER in DOSbox. D-Fend figures this out on it's own.
In the AUTOEXEC part of a Dosbox config the following code is generated:
mount c C:\DOSGAMES
C:
CD\
CD digger
Digger
Now say you mount C:\WRONGFOLDER as C:\
This means the folder C:\DOSGAMES\DIGGER is no longer available in DOSbox. If you do this D-Fend will still create a profile and a Dosbox config, it will just skip the AUTOEXEC part.
Solution? Reconfigure those mounts and D-Fend will take care of the rest.