I tried placing one of my custom pictures that I use as my spray in TF2 into the portals folder (as a VTF and a VMF), in hammer I tried to use it as an overlay and it was just purple and black checkerboards. I deleted it in game and tested the newest version of my map. In-game most of the textures had purple all over them. How do I fix this?

EDIT : Fixed. Solution : Delete ClientRegistry.blob

Located at: C:\Program Files\Steam\steamapps*User Name Here*\portal\bin