Just purchased two ATmega328P Xplained Mini boards. I can't get them properly connected in Windows 8.1. While I have Atmel Studio open, then plug in a board, AS opens an ATmega328P Xplained Mini board page, so AS seems to recognize the board. But, I can't open a RealTerm session, because there is no COM port associated with the board. Going to Win8 Device Manager, it lists mEDBG CDC, indicating that the device driver is not installed (Code 28). Clicking on Update Driver and having Win8 search automatically for driver software, Win8 says "Windows found driver software for your device (mEDBG Virtual COM Port) but encountered an error while attempting to install it. The system cannot find the file specified. If you know the manufacturer of your device, you can visit its website and check the support section for driver software". The message seems to contradict itself, saying it found driver software, but can not find the file. I searched the Atmel site, but couldn't find anything (easily).
Restarting the computer didn't help.
I can take the board to a different computer (outside lab) running Win7, and the drivers install, a COM port is assigned, and I can open a RealTerm session.
Same on both boards.