HP Deskjet Printers - Printer Stays Offline in Microsoft Windows Vista
In Microsoft Windows Vista, the deskjet printer connected Via USB stays offline. The option to turn the printer online is either greyed out, or has no effect.
To resolve this issue, perform the following steps:
Right click on the My computer icon and choose Manage, and click on Devise Manager.
In the Devise Manager there will be the USB root Hubs ( there may be multiple USB root Hubs) perform the following for all the root hubs:
Right click on the USB root hub and go to properties, and then to power management, and un-check the option "Allow the computer to turn off this devise to save power" in the Devise Manager.