[xunkn0vvnx]

Here is the situation, I have a Dell 700M Inspiron Laptop running windows XP. I have 2 usb ports and alternate between 3 devices - a usb mouse, my pocket pc cell phone, and a Western Digital Mybook External Hard drive.

All of a sudden my USB ports stopped recognizing my devices. It still sends power though because I can still plug in my cell phone to charge it. The problem is that the computer fails to recognize any devices anymore, even my mouse. I have uninstalled and reinstalled the drivers and restarted my computer several times, I even tried system restore.

It may have to do with the fact that I accidently unplugged my hard drive while it was still running without using safely remove my hardware. I have heard stories of western digital harddrives causing BIOS and motherboard failures.

Please help!

[ozrom1e]

Welcome to TSG....

If you are changing devices regularly on USB ports it is possible that the ports have physically worn out and are no longer making connection and if this is the case it would be more cost efficient to replace the motherboard becasue replacing the actual ports involves a lot of work de-soldering and resoldering etc and can be a mess if the wrong person does it.

If you change a lot of devices it is advisable to get a powered USB hub. When these wear out they can be replace easily or get a USB cable that has a male on one end and a female recepticle on the other end at the dollar stores for a buck, I use these and have gone thru three at present = $3.00 plus tax. even cheaper.

What does it show in device manager for the USB ports?

If it says working properly then the ports are more than likely worn out

Take your devices to another computer to see if they still work, if they do then the ports in your computer probably are worn out.

Do you have service pack 2 installed on your computer?

[xunkn0vvnx]

In the device manager, it says that "Unknown device" in port 1 and nothing in port 2. Plugged into port 1 is my cell phone and in port 2 is my usb optical mouse.

Would both ports simultaneously stop working from being worn out?

The thing is that the port still works because I can use it to charge my cell phone.

[ozrom1e]

Do you have service pack 2 installed on your computer?

You will need the Windows XP recovery software for the computer for this if you do not have then order gere:

Dell Ordering New Recovery/Installation disks On-line
http://support.dell.com/support/topi...68C&redirect=1

First step, Start, Programs, Accessories, System Tools, System Restore. Create a restore point and name it something like "Before USB Fix". This is to bail you out if something goes wrong during the following process and makes things worse.

Create a file with NOTEPAD containing the following lines and save it as FIX.REG

-------------------------- Use text after this line --------------------------------
REGEDIT4
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment]"DEVMGR_SHOW_NONPRESENT_DEVICES"="1"

-------------------------- Use text before this line --------------------------------

Double click on FIX.REG and say yes to the Merge Into Registry question.

Unplug ALL USB devices.
Open Device Manager.
View, Show Hidden Devices.
Uninstall all devices under USB Controllers.
Uninstall all devices under Disk Drives that you know are not present.
Uninstall all devices under Storage Volumes. Say no to any reboot prompts until you are finished. Also, if a Storage Volume doesn't uninstall, ignore it and move to the next one.
If you have a yellow ? with unknown devices, uninstall all of the entries there as well.

When this is done, reboot TWICE.

Reconnect the USB devices and see if they're recognized properly.

NOTE: If you have a USB keyboard and/or mouse, you'll have to modify the instructions and leave enough parts for those to function. I don't have one yet, so I haven't had time to modify the instructions.

[Dr_Acula]

I've just been through all this as my computer suddenly decided to stop recognising all the USB devices. Have done ALL the things above including twice deleting all references to USB hardware in system manager and the registry and rebooting whereupon windows then reinstalled all the USB hardware. It STILL wouldn't work.

Then I remembered the schematic of a modern PC power supply. Turning the PC off doesn't really turn it off as the motherboard is still powered. So I pulled out the power cord, waited 30 seconds and put it back in. Et Voila! USBs all working again.

My theory is that the USB driver has an internal microprocessor and it needed a reboot. I wonder how many PCs get taken to the repair shop with this problem, are unknowingly 'fixed' when the power cord is unplugged, and the repair guy gets all the credit for fixing the problem without having to do anything!

[berniecliffdon]

I just found this thread through a google search as I was having the same problem, I just thought I'd take the time to thank Dr_Acula for his solution as it worked first time.
I'm sure Im not the first person to be helped out with this problem by finding this simple solution.
Thanks

[Dr_Acula]

Great to hear it worked. Turning a switch off sure beats hacking the registry!

[sammos]

Worked for me too! Thanks a million.
(Never thought I'd be thanking "Dracula" for solving my PC problems!)

[Dagavu]

Hi there!
I've got the same problem; "USB device not recognized". But I tried to switch off the power, but it didn't work out because the laptop won't go off.. So the I can't take the power from my computer at once.. Can someone help me??

[BobJam]

Dagavu,

Huh??

Waddya mean "the laptop won't go off"?? Do you mean to say it is perpetually on, no matter if you depress and hold down the "Off" switch?? If that's the case, then I think there's something much more wrong than just a failure to see a USB device.

One thought on Dracula's idea of pulling the plug and thereby restoring the USB function when it's plugged back in. Try removing your battery, keep it out for a minute or so, and then reinsert it (your CMOS battery should still keep your BIOS intact) - that would be like pulling the plug and then replugging on a desktop.

[Dagavu]

I ment to say that when I pulled out the plug, it didn't go off. But I forgot to remove my battery! Anyhow, I tried to pull out the plug and waited for 30 seconds but it still won't recognize my USB device! It's so anoying. Sorry for my Englisch, I'm from Holland.

[Dr_Acula]

Back in the olden days pulling the battery out would reset a laptop. But I hacked a broken laptop a few years back and the main battery was charging a second battery, and that second battery was really hard to get to. Desktops are simple - mains power and a lithium cell to keep the CMOS working. But laptops don't seem to all recognise that standard. Maybe do some searching on the technical schematics for your make and model. I did read once about someone who took the battery out for 48 hours - maybe that is worth a try.

[PeterReaper]

I just tried both suggestions (disconnect power and registry hack/revoce all USB decices). Unfortunately, neither suggestion worked. :-(

I have a Logitech MX518 USB mouse and recently reinstalled Windows XP Pro. My MX518 mouse is only recognized as a "HID-compliant mouse", so I don't have all the advanced functions of the additional buttons.

Thanks anyhow for the suggestions!

[BobJam]

Here is a discussion forum dedicated to nothing but USB issues:

http://www.usbman.com/forum/UltraBoa...=1&SID=3939001

[freya72]

Dracula, you are a legend. Last time this happened I was actually in labour trying to get my camera ready to take to the hospital and had to reinstall Windows to get it to work! This time, pulled the plug on the computer and everything is fixed! Awesome.