I tested both v3.4-rc1 and v3.4-rc2 and the bug is on both rc, I could not log on to my session and get the same error message. I noticed one thing, if it can help, I get some error messages while launching dpkg -i to install the rc1 and rc2 kernels: This is the console output for rc1: letozaf@letozaf-pc:~/Downloads/kernel/3.4 rc1$ sudo dpkg -i *.deb (Reading database ... 501490 files and directories currently installed.) Preparing to replace linux-headers-3.4.0-030400rc1 3.4.0-030400rc1.201203312035 (using linux-headers-3.4.0-030400rc1_3.4.0-030400rc1.201203312035_all.deb) ... Unpacking replacement linux-headers-3.4.0-030400rc1 ... Preparing to replace linux-headers-3.4.0-030400rc1-generic 3.4.0-030400rc1.201203312035 (using linux-headers-3.4.0-030400rc1-generic_3.4.0-030400rc1.201203312035_amd64.deb) ... Unpacking replacement linux-headers-3.4.0-030400rc1-generic ... Preparing to replace linux-image-3.4.0-030400rc1-generic 3.4.0-030400rc1.201203312035 (using linux-image-3.4.0-030400rc1-generic_3.4.0-030400rc1.201203312035_amd64.deb) ... Done. Unpacking replacement linux-image-3.4.0-030400rc1-generic ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic Setting up linux-headers-3.4.0-030400rc1 (3.4.0-030400rc1.201203312035) ... Setting up linux-headers-3.4.0-030400rc1-generic (3.4.0-030400rc1.201203312035) ... Examining /etc/kernel/header_postinst.d. run-parts: executing /etc/kernel/header_postinst.d/dkms 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc1-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc1-generic (x86_64) Consult /var/lib/dkms/nvidia-current/295.40/build/make.log for more information. ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc1-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc1-generic (x86_64) Consult /var/lib/dkms/nvidia-current-updates/295.49/build/make.log for more information. Setting up linux-image-3.4.0-030400rc1-generic (3.4.0-030400rc1.201203312035) ... Running depmod. update-initramfs: deferring update (hook will be called later) The link /initrd.img is a dangling linkto /boot/initrd.img-3.4.0-030400rc1-generic Examining /etc/kernel/postinst.d. run-parts: executing /etc/kernel/postinst.d/dkms 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc1-generic is not supported ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc1-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc1-generic (x86_64) Consult /var/lib/dkms/nvidia-current-updates/295.49/build/make.log for more information. Error! Bad return status for module build on kernel: 3.4.0-030400rc1-generic (x86_64) Consult /var/lib/dkms/nvidia-current/295.40/build/make.log for more information. run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic update-initramfs: Generating /boot/initrd.img-3.4.0-030400rc1-generic run-parts: executing /etc/kernel/postinst.d/pm-utils 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic run-parts: executing /etc/kernel/postinst.d/update-notifier 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.4.0-030400rc1-generic /boot/vmlinuz-3.4.0-030400rc1-generic Generating grub.cfg ... Found linux image: /boot/vmlinuz-3.5.0-030500rc2-generic Found initrd image: /boot/initrd.img-3.5.0-030500rc2-generic Found linux image: /boot/vmlinuz-3.4.0-030400rc1-generic Found initrd image: /boot/initrd.img-3.4.0-030400rc1-generic Found linux image: /boot/vmlinuz-3.4.0-030400-generic Found initrd image: /boot/initrd.img-3.4.0-030400-generic Found linux image: /boot/vmlinuz-3.3.0-030300-generic Found initrd image: /boot/initrd.img-3.3.0-030300-generic Found linux image: /boot/vmlinuz-3.2.0-25-generic Found initrd image: /boot/initrd.img-3.2.0-25-generic Found linux image: /boot/vmlinuz-3.2.0-24-generic Found initrd image: /boot/initrd.img-3.2.0-24-generic Found linux image: /boot/vmlinuz-3.2.0-23-generic Found initrd image: /boot/initrd.img-3.2.0-23-generic Found linux image: /boot/vmlinuz-3.2.0-22-generic Found initrd image: /boot/initrd.img-3.2.0-22-generic Found linux image: /boot/vmlinuz-3.2.0-21-generic Found initrd image: /boot/initrd.img-3.2.0-21-generic Found linux image: /boot/vmlinuz-3.2.0-20-generic Found initrd image: /boot/initrd.img-3.2.0-20-generic Found linux image: /boot/vmlinuz-3.2.0-19-generic Found initrd image: /boot/initrd.img-3.2.0-19-generic Found linux image: /boot/vmlinuz-3.2.0-18-generic Found initrd image: /boot/initrd.img-3.2.0-18-generic Found linux image: /boot/vmlinuz-3.2.0-17-generic Found initrd image: /boot/initrd.img-3.2.0-17-generic Found memtest86+ image: /boot/memtest86+.bin done This is the console output for rc2: letozaf@letozaf-pc:~/Downloads/kernel/3.4 rc2$ sudo dpkg -i *.deb Selecting previously unselected package linux-headers-3.4.0-030400rc2. (Reading database ... 501490 files and directories currently installed.) Unpacking linux-headers-3.4.0-030400rc2 (from linux-headers-3.4.0-030400rc2_3.4.0-030400rc2.201204072235_all.deb) ... Selecting previously unselected package linux-headers-3.4.0-030400rc2-generic. Unpacking linux-headers-3.4.0-030400rc2-generic (from linux-headers-3.4.0-030400rc2-generic_3.4.0-030400rc2.201204072235_amd64.deb) ... Selecting previously unselected package linux-image-3.4.0-030400rc2-generic. Unpacking linux-image-3.4.0-030400rc2-generic (from linux-image-3.4.0-030400rc2-generic_3.4.0-030400rc2.201204072235_amd64.deb) ... Done. Setting up linux-headers-3.4.0-030400rc2 (3.4.0-030400rc2.201204072235) ... Setting up linux-headers-3.4.0-030400rc2-generic (3.4.0-030400rc2.201204072235) ... Examining /etc/kernel/header_postinst.d. run-parts: executing /etc/kernel/header_postinst.d/dkms 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc2-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc2-generic (x86_64) Consult /var/lib/dkms/nvidia-current-updates/295.49/build/make.log for more information. ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc2-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc2-generic (x86_64) Consult /var/lib/dkms/nvidia-current/295.40/build/make.log for more information. Setting up linux-image-3.4.0-030400rc2-generic (3.4.0-030400rc2.201204072235) ... Running depmod. update-initramfs: deferring update (hook will be called later) Examining /etc/kernel/postinst.d. run-parts: executing /etc/kernel/postinst.d/dkms 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc2-generic is not supported ERROR (dkms apport): kernel package linux-headers-3.4.0-030400rc2-generic is not supported Error! Bad return status for module build on kernel: 3.4.0-030400rc2-generic (x86_64) Consult /var/lib/dkms/nvidia-current/295.40/build/make.log for more information. Error! Bad return status for module build on kernel: 3.4.0-030400rc2-generic (x86_64) Consult /var/lib/dkms/nvidia-current-updates/295.49/build/make.log for more information. run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic update-initramfs: Generating /boot/initrd.img-3.4.0-030400rc2-generic run-parts: executing /etc/kernel/postinst.d/pm-utils 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic run-parts: executing /etc/kernel/postinst.d/update-notifier 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.4.0-030400rc2-generic /boot/vmlinuz-3.4.0-030400rc2-generic Generating grub.cfg ... Found linux image: /boot/vmlinuz-3.5.0-030500rc2-generic Found initrd image: /boot/initrd.img-3.5.0-030500rc2-generic Found linux image: /boot/vmlinuz-3.4.0-030400rc2-generic Found initrd image: /boot/initrd.img-3.4.0-030400rc2-generic Found linux image: /boot/vmlinuz-3.4.0-030400rc1-generic Found initrd image: /boot/initrd.img-3.4.0-030400rc1-generic Found linux image: /boot/vmlinuz-3.4.0-030400-generic Found initrd image: /boot/initrd.img-3.4.0-030400-generic Found linux image: /boot/vmlinuz-3.3.0-030300-generic Found initrd image: /boot/initrd.img-3.3.0-030300-generic Found linux image: /boot/vmlinuz-3.2.0-25-generic Found initrd image: /boot/initrd.img-3.2.0-25-generic Found linux image: /boot/vmlinuz-3.2.0-24-generic Found initrd image: /boot/initrd.img-3.2.0-24-generic Found linux image: /boot/vmlinuz-3.2.0-23-generic Found initrd image: /boot/initrd.img-3.2.0-23-generic Found linux image: /boot/vmlinuz-3.2.0-22-generic Found initrd image: /boot/initrd.img-3.2.0-22-generic Found linux image: /boot/vmlinuz-3.2.0-21-generic Found initrd image: /boot/initrd.img-3.2.0-21-generic Found linux image: /boot/vmlinuz-3.2.0-20-generic Found initrd image: /boot/initrd.img-3.2.0-20-generic Found linux image: /boot/vmlinuz-3.2.0-19-generic Found initrd image: /boot/initrd.img-3.2.0-19-generic Found linux image: /boot/vmlinuz-3.2.0-18-generic Found initrd image: /boot/initrd.img-3.2.0-18-generic Found linux image: /boot/vmlinuz-3.2.0-17-generic Found initrd image: /boot/initrd.img-3.2.0-17-generic Found memtest86+ image: /boot/memtest86+.bin done After having booted my PC in to these two rc, after trying to logon to my session and not beeing able to, I tried to reboot my PC clicking on the gear icon on the top right of the screen, selected shutdown and then reboot, but I had to switch of the PC pressing the power button as it got stuck.