when booting it says ubuntu, with Linux 2.6.38 this is because Backtrack is based on Ubuntu 10.04 LTS, Linux kernel 2.6.38.
There is indeed a small bug in the KDE 64-bit version where it hangs and keeps hanging (the lazy ****) after you installed and want to reboot.
There are a few workarounds:
1 When it asks after the installation to keep using the live version or reboot choose keep using live version, then open a console and type:
shutdown -h now when you pc is turned off just turn it back on and you good to go.
2 When your trigger finger was faster then you and you chose reboot after the installation and the lazy **** keeps hanging puch the power button of your pc and keep pushing till your pc is turned off and then turn it back on and you good to go.