I had the same problem with the PC at work, so here's what u can do to solve the problem:
Connect the USB Stick in any port, than go to: Control Panel > Administrative Tools > Computer Management > Disk Management
Scroll down until you see your USB Drive, right click on it and select " Change Drive Letter and Paths..." than click on "Change..."
Make sure that "Assign the following drive letter:" is selected and on the right side choose any letter you like ( i usually start from the end of the alphabet which would be Z
Now every time you plug in a USB drive it will be recognized as drive Z.
Hope it helps