Hi Everyone,
L3DT 11.11 has an error in the 'calc_HF_CurvFilter' function, which is used to smooth heightfields during erosion and at other stages. This bug causes the filter to fail for certain non-square map sizes (maps that are taller than they are wide). I have fixed this bug for the next developmental build, which will be available in the next week or so. I apologise for any inconvenience caused.
Regards,
Aaron.
Updated 7/Dec/2011: The fix is included in L3DT v11.12 dev build 2, which is now available for download.