I fixed this dead USB ports issue on my friends PC running Win8 Pro x64 on Asus P8Z68-V Pro (Intel Z68) by going thru these following steps:
- During POST, open up BIOS
- Enter advanced mode
- Go to "Advanced -> "USB Configuration"
- Set both "USB Legacy Support" and "USB3.0 Legacy Support" to Disabled
- Save and exit BIOS
- Log on to Windows
- Go to "Control Panel" -> "Windows Update"
- Remove KB275872
- Reboot and open BIOS again during POST
- Set both "USB Legacy Support" and "USB3.0 Legacy Support" to Enabled
- Save and exit BIOS
- After logon go to "Control Panel" -> "Windows Update" and hide KB275872 which now should be in "Important updates". Keep it hidden and uninstalled until it's confirmed this issue with the update has been fixed.
These instructions might help on other motherboards/chipsets/BIOS versions aswell.