I've experienced all of the mentioned scenarios, the long search, the full lock-ups, the hidden windows, the recovery of Poser when threatened with "End task". Don't we all love Poser?

Since Poser 7 it sometimes works to cancel Poser's search for textures, but not in all cases. So now I always apply any texture, if asked for a missing one. Mostly I just take the ground texture. When Poser is done with looking for missing files, I install the missing textures or make them or point the shaders to other textures.
Thanks for the tip, Johnny. I will try this.