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