I have Xubuntu 16.04 installed as the only OS on my Acer Aspire 5750 laptop. I have a BenQ external monitor connected such that I have a dual monitor setup (my laptop screen + BenQ).

When the BenQ monitor, connected to my laptop via HDMI, is not receiving a signal (which happens when the computer is off), it displays a message "HDMI No Cable Connected!" and presumably goes into some idle mode. When it is in this mode and I turn on the computer, the boot hangs and I see the Acer logo covered partially by a black rectangle's silhouette:

enter image description here

I set GRUB_CMDLINE_LINUX_DEFAULT="" in /etc/default/grub to attempt to see the boot messages, but nothing can be seen - the computer really freezes at boot. If I proceed by turning off the computer forcibly (hold the power button for 5 seconds) and quickly turn it back on again, which avoids the BenQ monitor from going into its idle mode and the boot sequence proceeds successfully. If I unplug the monitor and use my laptop's screen only, boot works nominally.

My question: what can I do to fix this boot freeze? Thanks for any suggestions!

  • Just FYI, this post might get duped to askubuntu.com/questions/162075/… so you might want to check that out, so that if it didn't fix it, you can mention that you tried it, so it won't get wrongly duped. Sep 25, 2016 at 21:12
  • None of the link's fixes work for me unfortunately. My problem is a true "freeze" - when I have the HDMI external monitor connected when I press the power button, all I get is a frozen part-covered Acer logo as shown in the picture. Grub, etc. nothing can be accessed with any sort of key combo. Sep 25, 2016 at 21:36

1 Answer 1


I just installed Xubuntu 16.04 on my old Acer Aspire notebook. Once installed, on reboot, I get the login screen, enter my correct password, the password dialog disappears, leaving wallpaper, and thats all -- never finishes activating the desktop. I have spent hours trying to find a work-around, with no luck. Here's what finally worked for me:

If I raise the laptop lid and then shut it, the desktop appears.

Next: -- select main menu. -- select 'settings' -- select 'display'.

It showed my external HP display selected as #2, followed by the Laptop (disabled).

There is a drop down which showed Laptop as the first option. Underneath, a check box for 'Use this display' (unchecked), and next, a check box for 'Primary display' (unchecked).

I used the drop down to select my monitor (which was listed after 'laptop'), which showed my monitor along with the correct settings. I checked both: 'Use this display' and 'Primary display'.

After rebooting, I logged in, and the desktop came up right away on the external monitor. I can only hope the open-shut laptop lid/screen thing works for you.

If not, and someone can fill in where the configuration file for the displays can be found in your home directory, you could do a control-alt-T, and use the terminal to edit the config file, and I suspect that would work.

I'm guessing the trick is to positively assert the external monitor as 'primary'.

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