Had a weird issue when setting up an Ubuntu Karmic JEOS VM under VirtualBox. When it was installed it rebooted and then the VM window dissappeared. I tried to boot it a second time and it got to grub and then as soon as I selected the kernel I wanted to boot again it crashed.
Kernel logs were showing that VirtualBox was segfaulting. I decided to take a look at the VBox.log for the vm and I found this:
00:08:38.967 VM: Raising runtime error 'PAEmode' (fFlags=0x1) 00:08:38.967 Changing the VM state from 'RUNNING' to 'FATAL_ERROR'. 00:08:38.967 Console: VM runtime error: fatal=true , errorID=PAEmode message="The guest is trying to switch to the PAE mode which is currently disabled by default in VirtualBox. PAE support can be enabled using the VM settings (General/Advanced)"
I then went into the advanced settings and turned on PAE. As soon as I did that the problem was solved and the VM booted without an issue.