Virtual Box not liking 64bit ISOs

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I have added the iso for a Server 2008 r2 to my virtual box, and tried to boot for the first time but getting the error as below

"VT-x/AMD-V hardware acceleration has been enabled, but is not operational. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot."

The CPU in my machine is 64bit so it should work fine, any ideas?

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for info, the motherboard I am using at home is: http://uk.asus.com/Motherboards/AMD_AM3Plus/M5A97/#specifications
and the motherboard at work is just the basic that comes with the HP Compaq 6005 pro

 

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Have you got it enabled in BIOS?
see here: https://forums.virtualbox.org/viewtopic.php?f=6&t=51827
(not exactly same issue). Virtualbox forum is a good resource for clues

 

Just tried it in VMWare Player and its working fine without any problems, all I can think is its a problem within Virtual Box for compatibility

 

Any reason you weren't running Player to start with?

 

I've always used Virtual Box as that's the one I started with and have kind of got stuck to, but I am fast moving away from that area now.

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I've always used Virtual Box as that's the one I started with and have kind of got stuck to, but I am fast moving away from that area now.