To reproduce, just right click in any folder you have access to and try to create a new folder. The menu option appears grey/disabled, but it still works. Also happens with pasting a file.
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: nautilus 1:3.4.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-21.34-generic 3.2.13
Uname: Linux 3.2.0-21-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0-0ubuntu1
Architecture: amd64
Date: Fri Mar 30 22:56:11 2012
GsettingsChanges: org.gnome.nautilus.window-state geometry '800x550+199+356'
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
ProcEnviron:
LANGUAGE=en_GB:en
TERM=xterm
PATH=(custom, user)
LANG=en_GB.UTF-8
SHELL=/bin/bash
SourcePackage: nautilus
UpgradeStatus: No upgrade log present (probably fresh install)
Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 933744, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.