This looks like typical tiled sampling, which is enabled by default in all 3ds Max texmaps....disable the 'tile' checkboxes in your texmap (in the UVW coordinate rollout) and see if the issue goes away.
It does make sense if the spline is closed...
However, capping should be skipped if the spline is open. Perhaps you found a bug in that switch...could you post the file so I can examine it?