Specified Port Unknown USB printer problem

I am trying to resolve a problem with a compuer at a non-profit organisation I am associated with. The problem arose following the connection and installation (attempted anyway) of a HP K5400 printer. The current state is that 1. the printer doesn't print and perhaps more seriously 2. there is a persistent error messsage that pops up on the computer that states " An error occurred during the installation of this device. The specified port is unknown ". Clicking "finish" on the rror message causes it to go away but it always pops back within 3 seconds. This happens independent of whether the printer is physically connected or not and I note that the computer always starts up with the message "detected new hardware" even when there's nothing on the USB ports other than the mouse. I've tried a number of things to resolve this including contacting HP support who responded with some procedures the most worrying of which was their instructions to refresh the USB port which had the effect of disabling the mouse (sometimes I can get it back with a restart). But nothing so far is eliminating this problem. If anyone has experienced this and knows of a fix I would like to know about it. The computer by the way is running XP Home Edition Ver.2002 SP.2

 

The attempted installation took place before I was sked if I could help and the person who did that installation has lef the organisation so I don't know the answer to the first question but I suspect installation was not done in the correct order.
Now tell me a bit about uninstalling USB devices. The HP support guys instructions were to uninstall the root hub, but there are are 4 root hubs not just one. Do I uninstall all of the root hubs, restart the computer and hope the USB ports come back? I was advised to have the Windows CD-ROM to hand at this point but you've probably already guessed - no one knows where it is. What are the risks of doing this? If I completely disable the computer I will need to find a hole to hide in so I need to have a better understanding of what I am doing here. First time I disabled the mouse a restart got it back. Second time it didn't but moving it to another USB port did, I was running scared by then. I don't think this computer has PS2 ports unfortunately.
I will check for Windows updates, that sounds prudent anyway.

 

Here are the instructions for uninstalling the drivers and software:
http://h10025.www1.hp.com/ewfrf/wc/...s&lc=en&dlc=en&product=2511767&dlc=en&lang=en
There is also a utility to do the job, see the section "Uninstall the software using HP's Uninstall utility ". Here is the download, BTW:
http://h10025.www1.hp.com/ewfrf/wc/...s&lc=en&dlc=en&product=2511767&dlc=en&lang=en

Here is the printer's webpage:
http://h10025.www1.hp.com/ewfrf/wc/...us&dlc=en&submit.y=5&submit.x=5&lang=en&cc=us
You will find the setup and installation instructions there.

If there are problems with installation, I recommend removing all traces of the software and [printer] drivers. Follow the instructions very carefully for reinstallation. Edit: If there is software and drivers installed for previous printers it could cause problems. Check In Control Panel -> Printers for previous printers.

In Device Manager under Universal Serial Bus Controllers, make a note (write down) the make and model of the devices labelled Controller in case you may "lose" them. If they are listed as "Standard...Controllers" the correct drivers may not be installed at all and if there is no "Enhanced...Controller" it will not be working as USB 2.0, only as USB 1.1. Post back if you suspect this.

Matt