Pro lighting skies - HDR works, light is purple?

Hallo to everyone who is using the addon “Pro lighting skies” from Blenderguru!

I have a annoying Problem after installing the Demo Version of “Pro lighting skies” :
The HDRi-maps in the background are all working fine - except the light coming from it.

All Objects are purple, i tried removing and installing the addon again,
but the problem remains.

The problem only appears on one particular scene, the one on which i really need Pro lighting skies,
on any other scene the addon works fine.

I previosly had a own HDRI map attached without the Addon and deleted it, to use a Preset from the addon.
Is it possible, that Blender still wants to use this map and gives me the purple “emty”-color because it can’t
find the map anymore?

I am new to the HDRI lighting topic and doesn’t know much about it, maybe there’s a simple trick to it?

Thanks in advance!