USB device not recognized

Try connecting it some other computers.
If it does not work at all, spend $8 to replace it.
If it does work, then it's either the "hardware" on your computer, or the Vista "software" (wrong/missing USB device-drivers).

1. Go to Start>> Right click My Computer>> Manage>> Device Manager 2. Expand the USB Controller section 3. Right click and Uninstall all of the listed USB devices 4. Reboot the system

Did this suddenly start to occur? Were they working before? If so, it is very simple - shut down computer, remove the battery and unplug any power source, wait a couple of minutes and reassemble and power up. Wala! I read all kinds of complicated instructions, started with the simple, and problem solved.

Try disconnecting all external devices and reboot your laptop.
You must have all USB devices disconnected, memory stick, USB mouse or keyboard, Hard drives, flash cards ect.
After a reboot check your device manager for flags or exclamation marks and remove if present.
Again, re-boot your laptop and check your device manager.
Ounce you have cleared all marks from device manager and all is clear,
plugin your first USB device and check operation.
Please check your equipment manual for details on what USB ports and speeds are available for your required devices.
Hope this works for you.
Please rate ASAP
Thanks

check the formats of the keys. if they are NTFS they might not be recognized by earlier Windows versions. What version of windows does the laptop computer use? It may be as simple as using the correct formatting (FAT or FAT32) on the USB memory key.

You mentioned that you uninstalled the unknown device from the Device manager. If you uninstall it then connected your usb flash drive you will see an error again on your device manager. This means that the driver for your usb port is not properly installed.

To install it, visit dell website, look for the model of your machine and locate the driver, download it then install from your machine.

if usb flash memory is working on other computer/laptop then do the following step.

Insert the usb flash memory.
Goto desktop, right-click my Computer, click Properties, click on Harware tab, click Device Manager button.

There should be yellow exclamation(!) sign showing Unknown Device
Right-click and select UnInstall.

Reboot your laptop
Insert the usb flash memory.

It should work.

its a driver issue most likly down to vista (as always) have you tried the latest updates from the microsoft website yet?

sounds like a bad usb cable

What operating system are you using? If xp/vista it should do it automatically. If 98 then you will need to get drivers from the makers website ;)