there were several posts of people dealing with non-working connections to the computer.
Please be aware that not all MicroUSB cables on the market are suitable for micropython boards.
Esp. those (cheapo) cables you can buy for only a few dollars/Euros/Pound/Yen stating to "charge your smartphone" might only carry out the power lines but not the data lines of the USB connection. Thus, those cables will nicely power the micropython board but there will be no data connection.
Try another cable before fiddling hours with drivers and system settings. Most likely the cable which came with your smartphone or other devices which can be connected to your computer will be ok.
There is a page on the wiki starting to deal with all kind of connection and driver issues. Please add your findings if they are not yet written (it's a wiki

http://wiki.micropython.org/Installation