Check your BIOS to verify that USB function is enabled if no USB devices are working on the computer. Also check device manager to see if your USB controller is listed. If the controller isn't listed, or if a warning icon appears, your BIOS may be outdated. If it is listed, R-click the controller and select properties to view any warning messages.
My USB flash drive (SanDisk Cruzer Micro 512MB) works with my office computer and my laptop but not my home desktop (where I also work -- so I need files there.) SanDisk support told me that there probably wasn't enough power in my USB ports, and suggested I buy a powered hub. I did, and that didn't make any difference. My computer doesn't recognize that anything has been plugged in.
Thanks for any suggestions.