I posted a message about my scanner early yesterday, but left out a bit of info, so I'm trying it again:

I've used my HP 4100C USB scanner without any problems for a couple of years, and now all of a sudden it's dead. My scanner does not have a power button, so I'm not sure if it's the power supply or not.

All I know, is that if I push the scan button on the front, I get absolutely nothing. If I go to the MS Windows Start button and run the HP Scanner software from the menu, instead of it powering up and scanning, I get a windows message telling me that I don't have a scanner!

When I go to the Control Panel and double-click the Scanners and Cameras icon, there is nothing there. The device manager shows my webcam up and running under the Image Device Section and the USB Controller section, but there's no sign of my scanner anywhere.

I've swapped the USB slots that my scanner and webcam use. The webcam works fine in both slots, but the scanner will not work in either one.

I've re-installed the scanner software several times. All the re-installs complete successfully, but I still get the same ol' "you don't have a scanner" message when I attempt to use it. If I attempt to uninstall it (via the HP uninstaller or via the Add/Remove Programs from the control panel), I get an error message telling me I can't uninstall it!

I'm at my wits end!!!

Any ideas, anyone?

Thanks in advance for your help!!!

It's quite possible the power supply is at fault. Check the output of the power supply with a multimeter and compare the reading with the rating on the power supply Asuming you have a external one (transformer) If it checks good, and good voltage, than open the unit up, and check to see if voltage is present inside. Be careful not to short the probes on the circuit board.

I have an HP 5200C scanner and have had the same problem. I have a COMPAQ computer and it was an initial nightmare to get this scanner properly installed. Occasionally the system seems to "lose" the scanner so I have to reinstall it periodically. Try this (it works for me): Go to Start-Settings -Control Panel-System and open Device Manager. You should see the scanner listed under Imaging Device. Double click on this and see if the scanner is listed. Open up the properties and see if it is listed. If the scanner should be listed twice you need to delete it. Unplug the scanner and uninstall the software. Close all programs except Windows. Put the scanning software CD-ROM in your drive. If should automatically start. If not click start, run and, assuming "D" is your CD-ROM drive then type D:\SETUP.EXE. From the menu that pops up select Install Scanning Software. A USB port is selected as default. The software installation will begin. After installation runs it will prompt you to select the cable. If you use USB make sure you use the correct cable. When "setup complete" appears select "finish". When the computer shuts down connect the scanner using the USB cable/port. Once the scanner cable is connected, plug the scanner into an electrical outlet. Restart your computer and, hopefully, you'll be good to go. I found alot of info on the scanners at www.hp.com/cposupport/scanners.