I have an HP laptop dual-booted with Windows 10 and Ubuntu 16.04. I'm trying to use a second monitor I have while using Ubuntu but I keep having the following issues:
Only the second monitor appears with a screen after I click "Detect Displays" in Ubuntu Display Settings
I can't open the display settings or a web browser once I connect to the second monitor
If I disconnect my VGA cable from my laptop I lose the second screen and my main screen doesn't come back. I have to restart my laptop to get back into Ubuntu.
I don't have any fancy graphics driver that I know of in my laptop. It uses an AMD APU so idk if that would cause any issues.
EDIT:
$ sudo lshw -C display
*-display
description: VGA compatible controller
product: Trinity [Radeon HD 7640G]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 1
bus info: pci@0000:00:01.0
version: 00
width: 32 bits
clock: 33MHz
capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
configuration: driver=radeon latency=0
resources: irq:37 memory:e0000000-efffffff ioport:3000(size=256) memory:f0300000-f033ffff
sudo lshw -C display
which will tell us the video hardware and driver in use. Thank you for helping us help you!