Sorry to revive an old thread, but I'm having this same issue. Whenever I attempt to start my pi, I get the same message as OP:
udev pre-start process (40) terminated with status 127
My pi has been running fine for about a week, but I restarted it this morning and am now getting the above message every time I try to start it.
Pi: Model B (512Mb ram)
OS: Raspbmc (latest)
SD: 32 GB - Patriot Class 10 (PSF32GSDHC10) - (17GB Free)
I've tried several different power adapters, and changing it seems to have no effect.