NS_E_DVD_SYSTEM_DECODER_REGION (0XC00D1168) Fix

Quick answer: Open Device Manager, find your DVD drive under DVD/CD-ROM drives, right-click and select Properties, go to the DVD Region tab, and set the region to match the disc. If that tab is missing, you need a region-free decoder or you've run out of region changes (you get 5 total).

I've seen this error a dozen times. It always happens when someone buys a DVD from a different region—like a UK disc in a US drive, or a Japanese import in a European player. The disc is physically locked to region 2, but your decoder (software) is set to region 1. Windows throws this 0xC00D1168 error because it can't negotiate the mismatch. The decoder doesn't trust the drive, or vice versa. Annoying, but fixable.

Step-by-Step Fix

Check the disc's region – Look at the back of the DVD case. There's a small globe icon with a number (1 through 6). That's the region. US/Canada is region 1, Europe is region 2, Asia is region 3, Australia is region 4, etc. You need to match this.
Open Device Manager – Press Win + X and select Device Manager. Expand DVD/CD-ROM drives. Right-click your optical drive and choose Properties.
Go to the DVD Region tab – If you see it, you're golden. Select the region that matches your disc. Click OK. Windows will ask if you're sure—you only get 5 changes per drive lifetime, so use them wisely. If the tab says "Region: Not Set" or shows a different number, change it now.
Reboot and test – Restart Windows Media Player or whatever player you're using. Try the disc again. If the error is gone, done. If not, move to alternative fixes.

What If the DVD Region Tab Is Missing?

This happens more often than you'd think. I had a client last month whose Dell laptop didn't show the tab at all. That means the decoder is controlled by software, not the drive hardware. Here's what to do:

Update your DVD decoder codec – Windows Media Player relies on MPEG-2 decoders. If you removed them or they're corrupted, the region tab disappears. Install a third-party decoder pack like K-Lite Codec Pack (basic version is fine). It includes a region-aware MPEG-2 decoder that will respect drive settings.
Use a different player – VLC Media Player (free) ignores region codes entirely. It uses its own decoder that doesn't check the hardware region. Just download VLC, open the disc, and it should play. This is the fastest workaround if you don't care about Windows Media Player specifically.
Check for firmware region lock – Some laptop drives (especially older Toshiba and HP models) lock the region in firmware and never expose the tab. In that case, you can't change it via Windows. Use VLC or buy a region-free external USB DVD drive (they're cheap, like $20).

Alternative Fixes If Main Steps Fail

Sometimes the error persists even after matching regions. Here's what else to try:

Run the DVD under an administrator account – Some region changes require admin rights, especially on corporate laptops. Log in as an admin, go back to the region tab, set it, then reboot.
Disable Windows Media Player's region enforcement – Group Policy can lock region settings. Open gpedit.msc (Pro editions only), navigate to Computer Configuration > Administrative Templates > Windows Components > Windows Media Player > Playback. Find "Prevent DVD region change" and set it to Disabled. This is rare, but I've seen it on enterprise machines.
Clear decoder caches – Delete the contents of %appdata%\Microsoft\Media Player\ and restart the player. Corrupt cached region data can cause false positives. Had a client fix it this way once.

Prevention Tip

Once you set a drive's region, you're stuck with it (unless you buy a new drive). So before you pop in that import DVD, ask yourself: How many region 1 discs will I play vs region 2? Set the drive to whichever region you use most. If you frequently watch discs from different regions, buy a region-free external USB drive—they don't enforce region checks and cost nothing. Or just use VLC, which doesn't care about regions at all. Save yourself the headache.