Just a FYI...
I installed a new bios (gigabyte z87 mobo) and my card (zxr) disappeared from control panel. Changed PCI-E slots and it was still missing. Removed all creative drivers, reg keys, the works and still couldn't get it to come back.
Re-installing windows fixed the problem.
I've noticed that you have to pull the power from your system when the card fails to show up sometimes for 2-3min. It might save you some time if it happens again.