USB Devices Not Recognized

[allanc]

I have a 5 year old desktop (XP PRO sp2) with 6 USB ports in total (4
in back, 2 in front).
The 4 in back are 2.0 but I am not sure of those in front.

I have not had a USB issue until recently when I changed my monitor to
one with 4 built-in USB ports.
I installed the monitor and software according to the directions.
I connected the USB cable to the back of the computer.
However, everytime the cable is connected, I am getting errors such as
'USB device not recognized'.
The device manager also shows unknown devices.
I delete the unknown devices and then try connecting the cable in a
different order such as before/after monitor is powered up, before/
after computer is powered up, etc.
I have also disconnected the power cable to the computer (a suggestion
from a computer help forum).

The USB cable from monitor to computer is now disconnected.
All USB devices that were connected at the time the monitor was
installed function OK (such as keyboard, mouse, printer).
However, a USB stick that I have used many times now displays an error
'USB device not recognized' whenever I connect it.
I have tried updating the USB driver but a message similiar to 'You
are already using the current driver' is displayed.

All suggestions are appreciated.

Thank you in advance.

 

[Bob I]

Perhaps there was a hardware problem with the monitors USB connections
and hub. As to the USB stick?!? Try it on another PC.

 

[allanc]

The USB stick is fine on another computer.
I have also tried multiple sticks on mine that don't work.

Should I replace the USB driver on my computer?
If so, how?

 

[Bob I]

First try just removing ALL the usb devices and let the PC reinstall them.

 

[Karl Snooks]

Allanc,
Your laptop has a limit on how much power it can supply to USB ports and
there is a limit on the number of root usb hubs. Does your new hardware have
its own supply for the USB ports which it supplies?
Karl

 

[allanc]

I am not sure what you are asking me.
You mean the monitor?

 

[Karl Snooks]

allanc,
The 4-port usb hub on your monitor-does the hub itself receive power from
your computer or from the usb port on your computer? Here I'm speaking only
of power for the hub itself and not for the monitor.

Try, using Device Manager, disabling all usb ports except for the one
feeding the monitor. If that works, then reenable other usb ports on your
computer one at a time.

karl

 

[allanc]

I found out that I can get it to work if I leave at least one other
USB device *not* connected to the computer.
As soon as I connect that printer, I get an 'unknown device' error on
the printer.

 

[Bob I]

Then you are likely exceeding the ability of the port to provide enough
power for everything you plugged in. Use a powered hub instead.

 

[allanc]

I assumed (obviously incorrectly) that the monitor hub would be
powered.
The additonal USB ports was actually one of the reasons for choosing
this particular model of monitor.

Thanks to all for their assistance.