I dread updating the kernel and rebooting to find the Ubuntu graphics aren't working and you have to manually intervene. This is usually because Ubuntu for whatever reason didn't update the drivers you need (eg. the manually compiled Nvidia Kernel driver that MUST be recompiled for each and every kernel update unfortunately).
The most common reason may be that "linux-source" hasn't been installed automatically on my system. I tried to manually reinstall the........
wget http://download.virtualbox.org/virtualbox/3.2.8/VirtualBox-3.2-3.2.8_64453_rhel5-1.i386.rpm
rpm -i http://download.virtualbox.org/virtualbox/3.2.8/VirtualBox-3.2-3.2.8_64453_rhel5-1.i386.rpm
error: Failed dependencies:
libGLU.so.1 is needed by VirtualBox-3.2-3.2.8_64453_rhel5-1.i386
libSDL-1.2.so.0 is needed by VirtualBox-3.2-3.2.8_64453_rhel5-1.i386
libXmu.so.6 is needed b........