I have the same problem I think. I recently upgraded from a Windows 7 machine that had no trouble to a Lenovo Y500 (which rules in case you are in the market) with Windows 8 and it can't even recognize it. I managed at one point to get it to recognize it but it still couldn't use it by going into general pc settings and selecting advanced startup then selecting troubleshoot and on restart selecting option 7 for disabling the driver signing requirement then installing the driver from a folder manually. Unfortunately now when I try to do the same thing again I get a message that there is no driver in the selected folder. I use this one
for general atmega flashing on small devices for school.