I just don't get it, it doesn't make a lot of sense... I'm running Arch Linux and have upgraded my kernel and Nvidia driver a dozen of times (always using the driver from the official repo though) and never had any problems.
But when you say that neither Nvidia or Nouveau is loading, it still sounds like they interfere somewhere, although you have disabled one of them. When you removed nouveau, did you also do "sudo updatedb && locate nouveau" aftwerwards? Maybe there is still something left behind and detected by a boot script. You might try that and also remove Nvidia driver and chech with the locate command what's left behind. Remove all files, reboot into runlevel 3. Reinstall Nvidia module (256.44), regenerate xorg, reboot into runlevel 5 and try starting X.
You probablmy have done all this already, but I'm out of ideas and that's the end of the road for my Linux-Nvidia knowledge
Anyway, whether it works out or not, enjoy your vacation!