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  • VM: Oracle VirtualBox 4.0.10 r72479
  • Host OS: Windows 7 64-bit
  • Guest OS: CentOS 5.6 64-bit

Downloaded a ready-made image of the guest OS from here.

When running, CentOS tells me:

Your CPU does not support long mode. Use a 32bit distribution.

CentOS's error message

Also mounting the original distribution's DVD doesn't work.
What's wrong? It happened me before with other OSs (in VirtualBox only) but now I actually need that.

Any way to resolve this or should I use another VM tool? Google search doesn't give much.

Edit #1
Some of my system's details:

CPU Type: DualCore Intel Core 2 Duo E7300, 2666 MHz (10 x 267)
Motherboard Name: Asus P5KPL-CM (2 PCI, 1 PCI-E x1, 1 PCI-E x16, 2 DDR2 DIMM, Audio, Video, Gigabit LAN)
Motherboard Chipset: Intel Bearlake G31
BIOS Type: AMI (01/26/08)

share|improve this question
up vote 3 down vote accepted

Does your host machine have hardware virtualization support (VT-x/AMD-V), is that support enabled in the host BIOS, and is the option for hardware assisted virtualization checked in the virtual machine configuration?

Having working VT-x/AMD-V is a requirement for running a 64-bit guest.

share|improve this answer
Hi stephen! I've got into my BIOS in order to check if I have there anything related to virtualization but I couldn't find anyhthing. Anyway at Edit #1 you can see my system's details. Could you tell if it's a compatible one? How/Where do I check that? I'm totally lost in this area.. Thanks a lot! – Poni Jul 15 '11 at 14:09
Nevermind, found the answer to that :/ Thank you anyway ! – Poni Jul 15 '11 at 15:12

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