System Information
Operating system and graphics card

Windows 8.1 64 bit
16 GB RAM
Processor: Intel Core i7-4470
MSI NVIDIA GeForce GTX 750 Ti

Blender Version
2.72b

Short description of error
Sometimes hair renders with GPU but not with CPU

Might be related to https://developer.blender.org/T41066
but not sure

see also http://blenderartists.org/forum/showthread.php?353958-Is-this-a-bug-Hair-not-rendered-with-CPU-but-with-GPU&p=2760759#post2760759

Exact steps for others to reproduce the error

Unfortunalety, this is not a simple issue. When I open a new (blank) file and create hair on a random object (like a UV sphere) there is no problem.
But I have an older file which I first created in Blender 2.71 where hair doesn't render with CPU render, only with GPU render. BUT: I tried this file on a different computer without GPU, and on this one the hair is rendered with CPU render totally correct.
So it's maybe not really a bug in Blender but rather a bug in the file. I also noticed that a new file with a UV sphere and hair has a size of 144 KB whereas my old file where I removed everything (at least everything I could find) has a size of 972 KB (with nothing but a UV sphere and hair in it).

I don't know what to make out of all this but at least I wanted to report it.

Thank you,

Ernst Hammann