Chrome Version       : 70.0.3538.110
OS Version: 11021.81.0
URLs (if applicable) : -
Other browsers tested: -
  Add OK or FAIL after other browsers where you have tested this issue:
     Safari: -
    Firefox: -
    IE/Edge: -

What steps will reproduce the problem?
1. Enable Linux
2. Open the terminal, install the latest Firefox stable as per https://www.reddit.com/r/Crostini/wiki/howto/install-firefox-quantum (Manual Method)
3. After installation Firefox loads and works perfectly well
4. about:support (in Firefox URL bar) shows
   - Version: "63.0.3",
   - Build ID: "20181114214635"
5. Click the "hamburger menu" in the Firefox UI, (top right corner "≡"), menu displays OK
6. Click on any menu item having a submenu ("About >", or "Web Developer >"), submenu appears
7. Click any submenu item (including the "<" back arrow) to completely and irrecoverably freeze the OS

What is the expected result?
That the operating system (and Firefox) remains operational.

What happens instead of that?
The operating system freezes completely. Power cycle is required to recover a functional system.


Please provide any additional information below. Attach a screenshot if
possible.

   - Any rendering besides the mouse cursor stops, both in Firefox, other Linux/Chrome/Android apps and the terminal
   - The mouse cursor updates but the UI (including any parts of the system UI and the shelf) is unresponsive
   - Keyboard is unresponsive
   - The only way to recover the system is to power cycle, by holding power button. Refresh+power also works and restarts
   - The OS recognizes the irregular shutdown (offers to restore windows) but chrome://crashes reports no errors

It is not possible to screenshot or screen-record at this point, I couldn't find a way to recover the OS one the above issue triggered. I'm happy to take a picture or record a video if that's helpful but I believe I have described everything such a recording might uncover.

UserAgentString: Mozilla/5.0 (X11; CrOS x86_64 11021.81.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36