I have a similar problem with some TeraiYuki2 textures, after some research i have found something of interest, the main runtime was on this place : G:Gfx-3DPoserTeraiYuki2
and the runtime with problems was on this place : G:Gfx-3DPoserTeraiYuki2-free

When  i was loading something from the TeraiYuki2-free runtime, Poser 8 cannot find the textures, i have looked on the material room and see this path for the texture in the drop dowm menu :

G:Gfx-3DTeraiYuki2free... (notice : the - was replaced by a ) 

After some experiments i have moved the runtime to  : G:Gfx-3DPoserFreeTeraiYuki2 and Poser 8 find the texture.

From my observations, if you have two runtime who start with the same characters Poser 8 get confused and miss the textures, the problem probably is on the code who search all runtimes for a texture.

Note : this is not reported to SM,  i am on the move until the mild of the next week and my travelling laptop don't have Poser installed, once i am back in my hometown my idea is to create a set of runtimes to demonstrate the problem.