Hey guys, I've used MGE XE for a long time and it always worked but suddenly an error message came up, when I used the "Distand Land Creation Wizard"

It says:

A fatal error occured creating the landscape textures. Distand Land Setup cannot continue.

The index is outside the range. It must be not negative and smaller than the listing.

Parameter name: index

Anyone knows what this is about?!
I uninstalled all texture mods I installed since then and also some else, but I don't have any clue what to do.

Any help is appreciated