There are a few issues with content, but they can generally be worked around.  One of the strengths of Carrara is the ability to alter models and shaders to work.

Often shaders must be tweaked.  Too much highlight and shine are common issues.  Just open the shader and adjust.

If you have a poser model and it opens in Carrara without its morphs, they may be external.  I use poser to open the item, then resave it with external morphs turned off.  The re-saved item then contains the morphs, and it works.

If you have some more specifics regarding the problems  you're having, someone can probably help.

Klebnor

Lotus 123 ~ S-Render ~ OS/2 WARP ~ IBM 8088 / 4.77 Mhz ~ Hercules Ultima graphics, Hitachi 10 MB HDD, 64K RAM, 12 in diagonal CRT Monitor (16 colors / 60 Hz refresh rate), 240 Watt PS, Dual 1.44 MB Floppies, 2 button mouse input device.  Beige horizontal case.  I don't display my unit.