If the devices are to recent, you may need to install some updated driver to use them.
The needed drivers should come with those devices or be available online from the makers of those devices.
You may have a faulty USB port on the computer itself.
Try with any other available port.
Your USB cable may be faulty. Do you use the same cable for several devices? After all, they probably use the same model of device plug. Try another cable.
Finaly, from the controll pannel, open the System applet.
Chose the material tab.
Click the Periferals manager button.
Look at the USB bus controller entry. Any red on yellow exclamation point? Any RED icon?
Double click the item with one of those icons.
Sellect the Driver tab.
Try rolling back to a previous version. (third button)
Try updating the driver. (seccond button)
If that don't work, try un-installing the driver then reinstalling it. (fourth button)
Electro, January 2012
