SOLUTION: Dell Laptops Hang on Reboot/Shutdown after Windows 8.1 update

I’ve recently encountered a pretty new issue involving some Dell laptops where the system will simply hang at a black screen, completely blank, when a shutdown or restart is initiated.  This behavior occurs following the installation of the free Windows 8.1 update.  There is no evidence present in the Event Log or anywhere else to indicate what might be to blame, and nothing on the internet that I could find references the issue.

In my case, I encountered the problem while setting up around 10 Dell Latitude E7240 (Latitude 12 7000 Series) notebook computers for my clients.  The solution, as it turns out, is pretty simple.

As usual, it’s a driver which is to blame for the problem.  I first stumbled across the solution while troubleshooting when I decided to disable the wireless adapters (Wi-Fi and Bluetooth) using the hardware wireless switch on the side of the computer before shutting down.  You’ll notice that while Airplane Mode is on, the system reboots/shuts down just fine.

It’s because of the Dell Wireless 1601 WiFi/BT driver that’s preinstalled; for whatever reason, the Bluetooth portion of it is incompatible with Windows 8.1.  Explicitly disabling Bluetooth also fixes the problem, confirming that this is the source of the issue.

To correct it once and for all, here’s what you need to do:

  1. Download this driver from Dell.
  2. Choose to Extract Without Installing and specify a location of your choice.
  3. Wait a few seconds for the confirmation dialog to appear, then click View Folder.
  4. Double-click the Install_CD subfolder to open it.
  5. Run setup.exe and follow the instructions.
  6. Reboot the computer.

The problem is solved!

I presume this most likely affects all Dell computers running the A01 version of the driver.  I hope this solution has helped you!

Post-disinfection Stop Error: c000021a

On multiple occasions over the past couple of years (since kernel-patching rootkits have become prevalent), I have encountered a particularly troubling STOP Error that most often technicians simply respond to by running a repair or clean install of the operating system. It looks something like this:

STOP: c000021a {Fatal System Error}

The windows Logon Process system process terminated unexpectedly with a status of 0x[various] (0x[various] 0x[various]). The system has been shut down.

Where [various] represents any number of hexadecimal error codes that may apply.

In this case, simply restoring the registry to a previous state as I’ve written about before does not correct the problem.

There are posts and pages to address this situation scattered across the internet, but nearly all of them offer different solutions, and most of them don’t seem to work. Microsoft has a page that relates the issue to Windows NT OS, blaming it on the PendingFileRenameOperations registry key which is often used by malware and antimalware to perform a rename operation on reboot. However, fixing this key as they suggest also does not solve the problem.

Most often, when it’s encountered post-disinfection, I find that the problem relates to an issue with a patched system file. I’m not certain, but it nearly always seems to be winlogon.exe.

Regardless, there is one and one only way to ensure the problem is corrected: find and replace the suspect file! There are multiple ways to accomplish this:

  1. Boot to a custom OS or slave the drive, check the system files (or run a virus scanner through them), and replace the faulty files with good copies (see below).
  2. Run a system file check from the Windows Recovery Console by typing sfc /scannow.
  3. Boot to an MS DART ERD Commander disc for Windows XP and run a system file repair from within the environment (this is my method of choice).

If you are forced to manually inspect and/or replace the files, I suggest checking for Company information and investigating any files which are missing the usual Microsoft Corporation info. If a suspect file is encountered, check its MD5 hash and Google it to see if it’s a known patched copy.

Once the culprit(s) has been identified, navigate to the system32\dllcache folder and copy the corresponding file there to its correct location. If it isn’t there or the copy is also bad, restore it from the Windows CD, or look for a folder called \i386. You can also run a search for the file throughout the entire Windows directory to find copies which have been downloaded for Service Packs and other Windows Updates. Just be sure to get the correct version.

In my most recent customer’s case, the files at fault were explorer.exe and winlogon.exe. Both had been patched by a rootkit and needed to be replaced. Once that was finished, the system booted up just fine.

If you’re looking for computer help in the Louisville area, look no further.  Call me today and get it done right!