Usually, DDS images should have a pair of power-of-2 dimensions. They don't need to be squared, e.g. 512x128 is suitable too. But power-of-2 sizes are very recommendable to support MipMaps down to 1x1 pixels.
Unfortunately, DDS images with non-power-of-2 sizes do exist. And one of them makes XnView crash during the creation of preview pictures for a directory.
Example: http://www.ligh.de/PlaneShift/character ... sophia.dds
XnView crashes on non-power-of-2 DDS
Moderators: helmut, XnTriq, xnview