I can confirm I am having the same issue.
I am using a HP Z800 workstation (Just in case it matters - Dual Xeon's - X5570, 12GB ECC RAM, Quadro 5000, Intel 320 series SSD, Intel USB2.0). My Z800 was running Win 7 Pro 64-bit with no issues. I deleted the partition on my C Drive on my Z800, then formatted it, then clean installed Win 8 Pro 64-Bit.
The 5D Mark III is detected fine in Windows, no errors and listed correctly.
I have tried setting the program as 'run as an administrator'. I have also tried running in all the Compatibility modes. I have 9 USB ports on the Z800, I have tried all of them. I have also tried running off a powered USB Hub. None of these things helped, the issue is still there.
I believe this is likely to be an issue with the Canon software and we will need to wait for an update or new version from Canon.
Happy to be proved wrong of course 
Hi.
Since it's work on Windows 7 64-bits, but doesn't in Windows 8 64-bits, I think it's a Windows 8 issue. If I were you, I won't be the first to use any new OS... most OS always have issue during initial released.
By the way, I run the Windows 8 Upgrade Assistant on my Computer and I was surprise to see that it's mark "Microsoft Visual Studio 2010 Professional " as not compatible. If "Microsoft Visual Studio 2010" is not compatible with Windows 8, I wonder how the software it's develop will be able to compatible with Windows 8??
Have a nice day.
I've been running both VS2010 and VS2012 side by side on windows 8 for a month or two since the RTM came out. There are have been no issues with it preventing development.
That being said, I did check device manager and there aren't any driver issues, and no exclamation points.
When I hook up the camera windows detects that it is there and opens up the special camera window where i can see the battery left on the camera and how full the memory card is. I can even launch the EOS utility from there, but it's the EOS utility not picking it up.
My suspicion is that there is *something* hardware wise on my machine blocking access to the camera for the EOS utility.