I encountered an error upon arriving at the Pyramid near Neko Village. I can click Retry to make it go away, but it just comes back after a few seconds. Not to mention, but the background music doesn't play upon entering. Here's a screenshot. 
It's quite a well known bug in here. This is strangely the only area that does this, and I'm guessing they forgot to change a bit of the code to reference the rpgmvo file that is the exact same.
There are two fixes to it: a temp solution and a tested solution that is reliable (until the next update that is.)
Reliable solution:
To fix it, find in the audio folder bgm, and find two files that state "El Infausto Landron de Joyas A.rpgmvo" and "El Infausto Landron de Joyas B.rpgmvo"
You'll want to copy them (just in case of corruption) and change the names respectively to "El Infausto Landron de Joyas A.ogg" and "El Infausto Landron de Joyas B.ogg"
Temp Solution:
You can do what I did first time playing it, which was spam the enter key until I got to the underground section, save the game, and refreshed the game. That also seemed to work as a fix.
Unfortunately renaming them didn't work for me, for some reason. As an additional temp solution, go to google and play some desert music on youtube, and spam enter at all times in the area until reaching the underground section . I've found the Super Mario Bros. DS desert level theme works best with fetish games for maximum immersion.