Matt,
ESXI 5 U2 was just released a month or so ago and I would recommend upgrading your host to this version (and if you have Vcenter do the same). 2012 can work on U1 but it is not supported and can act quirky.
U2 fully supports 2012 and I suspect will resolve your issues once you can select the OS operating system as 2012.
http://www.vmware.com/support/vsphere5/doc/vsp_esxi50_u2_rel_notes.html
