To add on to this...

When this happens the machine gets extremely hot, locks, up and the caps lock LED starts flashing. The only thing to do at this point is do a hard reset (hold down the power button). I've also noted that as of my last post, putting it the machine in suspend mode sometimes results in the freeze with the caps lock key blinking, although no overheating. I'm stumped as to what the heck is going on...

This has been happening to me. At first when I was on the stock Ubuntu 14.04 LTS that came with the machine, it would just not wake from sleep reliably. I loaded Ubuntu 15.04 on to see if an updated kernel would help, and now it is doing what you describe, and the caps lock key is flashing when I open the lid.

Have you changed from the stock Ubuntu image at all?

I'm currently running the stock Ubuntu 14.04 LTS with the updated kernel to address the trackpad issues.

This exact thing is happening to me as well.  I have a 2015 Dell XPS 13 9343 that came stock with Windows 8.1.  I immediately dual booted it with Ubuntu 14.04 which I was having lots of trouble getting to work, and so I tried again with 15.04 which I am now successfully running.  However, I get the same symptoms when suspending; locked up, overheating, with the flashing caps lock key.  I just walked back from class after suspending and putting it in my backpack, and it was almost too hot to touch.

This has happened to me once so far.  I've had the machine about a week.  I have not been able to reproduce it.  Scared me.  Would love to hear some response from the Devs on this one.

So, best experience so far: Ubuntu Gnome 15.04. use tweak tool to set lid close to hibernate (not suspend) and it works like a charm! I left it for two days in hibernate and when i opened it i had an almost full battery and it had obviously been off the whole time.

Two of us in our office are using this setup and it is working the best of any other combo we have tried.

we have tried:

1. Debian jessie
2. Stock Ubuntu
3. Ubuntu 15.04
4. OpenSuse
5. Ubuntu Gnome 15.04

- Tor

Not sure if Unity Tweak Tool is any different in 15.04 vs 14.04, but I'm not seeing that option.

I experienced this issue when I installed TLP - disabling it solved the suspend problem (but obviously battery life suffers - I'm still to play with powertop and other power saving utilities to find a solution that works reliably).

My suspicion is that somehow the Broadcom driver does not play well with TLP, so having changed it to an Intel module I will give TLP another try. It just takes a lot of time to experiment with all the options to find out which works best for you :(

Also, there are some interesting improvements in the works for future kernels, see https://mjg59.dreamwidth.org/34868.html

I also experience this issue several times a week. It drains more than 25% of the battery in under an hour.

I did all the upgrades (kernel, trackpad, ...) and still on 14.04.

A temporary fix I have found is to disable WiFi and then manually click suspend. It hasn't happened since I started doing this. Yeah it's a bit annoying to have to do this every time I close it, but it's better than having it freeze up and drain the battery.

I think this further confirms its an issue related to the network card.