I'm back here with the same issue (Blank screen probleme).
I've updated to OSX 10.9.4, installed new Nvidia drivers and Cuda, and it was fine.
But if I change something into the system, like enabling SSD Trim or installing audio kext, the issue is back again and I've got to boot with nv_disable=1.
I've already tried to uninstall and re install web drivers but the issue is still here....
any idea ?