Hair hangs up rendering on one of three machines

I have an animated character with particle hair, nothing fancy. Because of some water material FX I’m rendering on 3 different machines. On two of the machines (call them A & B), rendering proceeds as expected. But on machine C, when the rendering “parts” (I’m using a 4x4 matrix) hit the portion of the image were the hair is to be rendered, it hangs, apparently forever. I’ve let it cook for a hour or so and no additional raster lines are drawn. I’m using Blender Internal.

Basic machine specs:
A: Athlon 64 5600+ CPU, dual core; 3Gb RAM; ATI Xpress 700 (legacy) graphics card, current drivers; Win Vista 32-bit
B: Athlon 64 2000+ CPU, single core, 1Gb RAM, ATI Xpress 200 (ultra-;egacy!) graphics (integrated); current driver; Win XP Media Center
C: Pentium 4 dual processor; 3Gb RAM; no-name integrated VGA graphics; WinXP Home Edition

I could understand if the the C machine’s graphics won’t let some aspects of the display not work well, but should it hang up the rendering pipeline? I’ve rendered hair on this same machine in Blender 2.49 and up to 2.57. I’m now using 2.59. It was always slow but never like this. Note that Blender does not crash, its memory usage is very reasonable, but it simply will not continue to render the image parts that have the particle hair in them.

Any ideas why this might be so?

Addendum: Tried another file, same character, different setting, no water. Also hung on machine C when trying to do the hair. Hair is very simple as particle hair goes, not a huge number of strands or children, uses Strand render and the material is not Traceable.

Followed up with some testing, got some interesting results on machine C:

  1. Having the particle system visible in the UI slows Blender down to less than a crawl – anywhere from 10 - 15 seconds between the time something is clicked on and the action takes place. Hiding the particle children helps some but having the system visible still slows things down a great deal. Hiding either the system (in the modifier panel) or the wig object frees up the UI.

  2. Other particle hair systems (all much more complex in terms of parent strands and children) do not cause the problem. One I had made for the earliest version of the character and since revised works just fine in both the UI and when rendering. Others made in other files both display and render without issues, other than memory limitations (that happens on all machines).

  3. The hair material does not seem to be part of the problem, since changing it does not change the situation at all.