When my computer returns from sleep or standby mode the attached Canon LIDE 25 USB scanner loses connection to the computer. This can be remedied by unplugging and reconnecting the USB cable. How can I stop this from happening? Changing the USB cable and the USB port does not fix the problem. The computer is running Windows XP.

This is a problem which I have seen on numerous occasions. As the computer goes into sleep or standby mode, Windows normally powers down the USB ports. Then when the computer returns from sleep or standby, the USB ports regain power but the device attached to the port does not reconnect properly. The best way around this issue is to instruct Windows not to turn off power to the USB ports when going into sleep or standby modes. To do this, go to the “Start” menu > “Control Panel”. In the Control Panel window open the “System” control panel (you may need to first select the “Performance and Maintenance category”). From the System Properties window click the “Hardware” tab and the “Device Manager” button. You should see a branch node in the Device Manager window named “Universal Serial Bus controllers”. Expand this node and you should then see several leaf nodes named “USB Root Hub”. For each of these “USB Root Hub” nodes, right-click on the node and select “Properties”. In the window that appears click the “Power Management” tab. Untick the option “Allow the computer to turn off this device to save power”. Click OK. Once this has been disabled for each of the “USB Root Hubs” you can close the Device Manager window and the System control panel window. Now power should no longer be turned-off to the USB ports when the computer enters sleep or standby modes. However, be aware that power will be turned off to the ports (and all other devices) should the computer go into hibernation mode, regardless of whether the above setting has been ticked or unticked. This is because hibernation mode copies all active data from RAM to the hard drive and then completely powers-down the computer. Therefore, unless you need to use hibernation mode it may be advisable to disable hibernation. This can be done by opening the “Power Options” control panel (you may need to first select the “Performance and Maintenance category”) and in the Power Options Properties window that appears click the “Hibernate” tab. On this tab untick “Enable hibernation” and click OK to save and close the window.