I have seen the same sort of thing, from time to time.    Poser prompts me to find a texture for one set I use, the texture being called "Metal7", or "Steel7", or something like that.   The first time it happened, I realised there were only six Metal/Steel textures, so I just clicked on number 6 and Poser was happy.   Since the result was OK, too, I suspect number 6 was the one that had been intended all along.   I think it's always best to apply some texture, since you can always replace it afterwards, rather than asking Poser to stop searching.   I seem to recall how stopping the search made Poser go off to sulk in his tent, as you have found, but I don't think that I ever found a way around that, so I haven't risked it in a while. 

Sometimes, when Poser hangs, it is because a new message window has popped up , but it is hidden behind the main one, or behind the preview.   That ought to be detectable as a separate entry in the task manager, however, so I assume it doesn't happen in this instance.