I am seeing the identical issue on an Intel DQ35J0 motherboard with SATA drives. (ESXi 4.1 worked great on this system.)
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did more research, found a solution that works for me.
With ESXi 5, ESX no longer uses MBR for boot, it has gone to GPT-based partitions instead. Which is fine, if your BIOS (and mine) supported it correctly. More details here: http://communities.vmware.com/message/1822854?tstart=0
There are two ways past this:
1) try changing your BIOS to enable UEFI support - then re-install completely. This did not work for me, I got purple screen of death when trying to do the ESXi install. (I chalk this up to problems with UEFI implementation in the BIOS revision on my older motherboard.)
2) Re-install ESXi 5, and during initial install press Shift-O when prompted. Add formatwithmbr to the options, proceed with install.
This second approach worked great for me, hope it helps.
-Michael