Can't install 12.1 on a VirtualBox under Windows 7

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http://askubuntu.com – I've just been looking at a load of similar issues to this but none have a fix that works for me. I've got a Windows 7 64bit i7 system on which I'm trying to install Ubuntu 12.1 (32 and 64) under a VirtualBox VM. I've tried booting from an ISO and from a disc and the furthest I can get is the boot options. If I try to run without installing or install it moves on and then simply crashes it seem (just blank screen with the cursor, not blinking). I've tried with nomode, no acpi etc as suggested in related questions. To test I tried installing Fedora as well and that caused a kernel panic but (HowTos)