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Ok this one gets a little bit complicated but bear with me :D

A client brought her computer in to be fixed about a week ago, she says she tried charging a new phone she bought from china and immediately after her USB keyboard and mouse stopped working (typical).

I had a quick look at it but because I did not have time, I did a simple system restore and it seemed as if the issue was fixed. I promptly sent it back to her but a few days back she called saying that the issue has returned. Turns out the computer was riddled with some virus that also corrupted her XP install so I had to format the whole thing (yes I tried repairing). I hoped that the format would fix the keyboard and mouse issue but the whole thing has escalated and the computer will throw the "USB Device not recognized" error when I plug anything into the many USB ports it has. I have installed all the drivers (including the chipset drivers) for the PC and even tried the unplugging from the power for a while trick, still no luck. I am sure it is not a hardware issue, but may be wrong.

This is way over my head. Can anyone help?

Computer: HP Compaq DC7100, Intel Pentium 4, 512mb RAM

OS: Windows XP Professional SP2

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1  
Sounds like China to me. –  digitxp Dec 29 '10 at 5:28
    
Did you unplug the PC from the power supply? online-tech-tips.com/computer-tips/usb-device-not-recognized –  Aki Dec 29 '10 at 10:24
    
Was wondering why my PC booted fine on Mondays. It was unplugged during the weekends, that was the secret. Switched off all the USB-booting options in BIOS and now it doesn't try to boot from USB devices. That was the cure in my case. –  Aki Dec 29 '10 at 10:42

2 Answers 2

up vote 2 down vote accepted

Being the sleuth I am (not), it's quite apparent that this phone is the cause. It's probably not entirely responsible for the viruses (though it could be, not difficult for it to launch an attack while plugged it), and it's quite possible that the phone overloaded the USB port with power.
I got a fake iPod in Hong Kong that came with a USB wall charger that I plugged my laptop fan into, and the thing doesn't spin anymore. Which is why I buy expensive stuff now at the sacrifice of my hopes of getting a new coat.

Try booting into an Ubuntu LiveCD. Does it work there? If it does, then it's software. If not, it's a hardware issue.
Do the mouse and keyboard work on other computers? If they do, it's a problem with the hubs and possibly the motherboard.

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Im starting to think more and more that its a hardware issue with the motherboard too. I remember the keyboard not working when I was in the (Press any key to boot from disc) bit when formatting, I have been using a spare ps2 keyboard ever since. Thats it, I am done wasting time on it, Im just going to transplant her hard drive, dvd drive and ram into onto one of my un-used machines. I might also chuck in an extra piece of ram to make up for the disgusting shell it comes with, either that or I will switch mother boards. I will get back to you with what I ended up doing. –  Franky Chanyau Dec 29 '10 at 5:43
    
@Franky Smart move, keeping a PS2 keyboard and mouse with you. –  digitxp Dec 29 '10 at 6:01

If everything else is working in the same port try using a USB extender. That happend to me and the fixed that.

If that's not the problem then the computer dosen't have enough power to supply it.

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