Re-affirming what 1DanK said. Carrara's cylinder map contains an errant row of polygons. It can be repaired by hand in the UV mapping pop-up but it is annoying to do (and to have to do). The picture linked in the first post appears to be showing the usual effect (as in, a one-poly wide section of crunched texture). Oh; bug was reported back in February, but I'm getting suspicious I've been put on the "ignore this user" list. Another report of the same bug might actually get someone to look at it.