Hi ! This is not really a question, because I have found a solution,but I think that this topic will help People who could encounter the problem.
Working on my Museum project,I recently changed the wall texture by a new stone wall texture, created under Photoshop with my graphic tablet.This to say that it is not a procedural texture,but a JPG picture.
My walls are subdivided planes, got by extrusion of the floor grid.
The previous texture had not precise shapes,so the angles didn’nt need an accurate tweaking for merging.
The new one is more detailed and needs separate planes and merging on the borders beetween planes.
I discovered that on a column of square faces,the texture was shifted. I couldn’t fix this with the Offset parameters in the Map input panel.
I have by chance solved the problem applying a subsurf level of ZERO,to my walls !