I have the same issues..  Exactly the same issues.  Contacted dell support and they asked the standard roll of questions, told them I didn't pay $4000 to be a guinae mouse and work my development laptop in safe mode to figure this out for them.  Answered all other questions, had the most updated bios (1.1.2 I believe), all drivers are updated through windows update, and alienware command center.  Alienware command center is updated... 

This isn't hindering the computer from being 98% awesome, but I WILL return this if they don't figure it out because spending $4000ish to have something that reminds me of a used car is .

Finally out long enough to run the keyboard diagnostic test and fail in support assist.  I will give Alienware props for generating a support ticket automatically from that, aside from this stupid keyboard issue, I've been very impressed.

And this is for an alienware x15 laptop, less than one week old..  Even typing this sentence there were missing keys that I KNOW I typed.

Performance is less than 39% as I typed this again..  Again the first letter of this sentence failed to type, forcing me to go back and re-type the p.  Last comment above failed on the A.  And to answer the questions I can already hear, this isn't strictly related to capitalized letters, sometimes lowercase letters drop (no shift key in use).  Then sometimes the entire keyboard stops responding (still looks pretty and lit though!)

Hey Crimsom,

the laptop is literally brand new, if I need to vacuum it from the factory, that’s messed up.

regarding the external keyboard..  just dropped 4K$ on this thing, and would’ve bought a desktop if I wanted to used an external keyboard.

thank you for responding though, attention to this issue is appreciated

I would simply run a keyboard test in support assist and then call support for a replacement. then before shipping remove your Personal data off of the drives and take them out so you can put them in the new laptop.

Experiencing a similar problem. I got this computer less than two weeks ago. It's not my primary computer so I've only used it a couple of times so far. Tonight the entire row of keys from tab to qwerty and on stopped working along with a few towards the bottom right. They'd stop working entirely then press multiple times then stop working.

I ran all the online diagnostics, updated every piece of software, driver bios that I could, tried  uninstalling the keyboard, I even did a factory reset and it is still broken. Feels like this must be a factory defect?

It's not a solution, but I have found a workaround... When the keyboard completely stops working, I close the lid, wait a few seconds, and then open it up again. That has fixed it for me every time. No idea what is causing this, but I do get that "sound" when devices are removed and then plugged into your USB port. So, and this is mostly speculation based on observing the pattern a few times, but it feels like the keyboard is getting "unplugged" from the laptop for some strange reason (because it is the laptop's built-in keyboard...) and closing then reopening the lid "plugs it back in"... 

I second what crimson is saying. Return it and get a new one.