Diagnose and repair hibernation problems

My Vista laptop kept losing its Internet connection when it came out of sleep mode. It turns out that the problem was related to the Dynamic Host Control Protocol (DHCP) Client service, or dhcpcsvc.dll, which tried to rewrite routing information to the network store interface. This caused a failed write operation that deleted the routing information.

Microsoft released the fix for the problem last September, though the patch didn't find its way onto my notebook until several months later. The machine's network link still hiccups for a few seconds when it comes out of sleep mode, but eventually, it restores the Internet connection on its own.

While this and other Windows patches won't address all the sleep and hibernation problems afflicting Windows users, your first step in solving problems with the operating system's power-saving modes is by downloading and installing the latest updates via the Windows Update service.

Here's a rundown of the most common glitches related to Windows' sleep and hibernation modes, and possible fixes.

Activate hibernation
If your PC has lost the ability to hibernate, you may have deleted your hibernation file when you ran Vista's Disk Cleanup utility. Regardless of why your system balks at entering hibernation mode, you can re-enable the feature via the Command Prompt: right-click the Command Prompt (it's located under Accessories on the Start menu), and choose Run as Administrator.

At the prompt, type powercfg -a and press Enter. You'll see a list of all the hibernation modes your system supports. Type powercfg -h on and press Enter to activate hiberation, or powercfg -h off to deactivate the function.

Check Vista's power settings
In Vista, press the Windows key, type power options, and press Enter. Click "Change when computer sleeps" in the left pane, select "Change advanced power settings" at the bottom of the Edit Plan Settings dialog box, and click the plus sign to the left of Sleep to view your sleep and hibernate options. If the Hibernate option is missing from the Start menu's shut-down section, change the "Allow hybrid sleep" setting to Off.

Update your video driver
A common source of Vista hibernation woes is an out-of-date video driver. Slowly, video card makers are updating their drivers to work smoothly with Vista. Go to the Web site of your video adapter vendor, and look on its Support or Downloads page for an update to your model's driver. To find out which video card your PC uses, press the Windows key, type device manager, and press Enter. Click the plus sign to the right of Display adapters to view the model(s) installed in your system.

Look in the Event Viewer
To open Vista's Event Viewer, press the Windows key, type event viewer, and press Enter. Check the error logs for one occurring when the hibernation glitch struck. Search the Web for information about the Event ID, or click the Event Log Online Help link to go to a Microsoft Help and Support page.

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