All peripherals require device drivers, including mice, keyboards, cameras, and USB keys. The reason you often don’t have to install these drivers is that most machines come with some basic USB drivers, including HID drivers (human interface drivers) which work with most mice and keyboards, and USB Mass Storage Class drivers which support USB drives. If a device isn’t fully supported by these basic drivers, you’ll need to install additional drivers. Your optical mouse, for example, may have features that aren’t built into the generic HID driver.

There may also be power issues. For USB devices that draw power, like optical mice and hard drives, a powered hub might be necessary.

You may also have wiring difficulties:

If you’ve noticed a difference between the USB ports on the front and the back of the machine, it may simply be that the ports on the front aren’t connected properly: often front-mounted USB ports connect to a spare USB header on the motherboard, and because design can vary from motherboard to motherboard and from computer case to computer case, they often break these connectors down to the individual pin level rather than a block with all of the connectors. If any of these pins have been inadvertently switched (± pins reversed for example), it could result in improper USB peformance, or even damage to the equipment you connect.