I just got Ubuntu 15.10 installed on my mac machine. Initially everything works well.

Following [the help.ubuntu.com tutorial on fixing the touchpad (for utopic)](https://help.ubuntu.com/community/MacBookPro11-1/utopic), I installed a bunch of things and did some config. After that I restarted `lightdm` with

```
systemctl restart lightdm

```

which consequently did a reboot. But it got stuck at shutting down so I ended up forcing the shut-down. When I re-started it I kept seeing many lines of 

```
 [drm: intel_pipe_config_compare [i915]] *ERROR* mismatch in ips_enabled (expected 1, found 0) 

```

while starting `WPA supplicant` in the process of starting `Light Display Manager` and was not able to boot into Ubuntu. I tried rebooting it many times but I was greeted by the same error.

[![enter image description here](https://i.stack.imgur.com/30rhg.jpg)](https://i.stack.imgur.com/30rhg.jpg)  

(Click image to enlarge)

What is going on? Without reinstalling Ubuntu, is there a way to fix this?