Strange Wavy Lines in Sampler

Hello everuone!

I'm pretty new to 3D Sampler, but I've noticed while messing around with some textures that these weird jagged lines appear. As I'm jsut practicing this is a free texture that I've used before in other programs so I know it's not an issue with the maps themselves (plus it happens with every photo I try).

I'm hoping there's a way to fix it.