I installed Lubuntu-core (via 18.04 mini.iso) on a USB flash drive and it works great with one monitor. When I plug in a second monitor on the same card and set the displays to be joined rather than mirrored, the screens become unreadable. Mirrored works fine. I tried adjusting the resolution and refresh rate for both, but couldn't find a combination that worked.
$ lspci -nn | grep -E 'VGA|Display' shows 01:00.0 VGA compatible controller : Advanced Micro Devices, INC. [AMD/ATI] RV370 [Radeon X300] [1002:5b60] 01:00.1 Display controller : Advanced Micro Devices, INC. [AMD/ATI] RV370 [Radeon X300 SE] [1002:5b70]
I have used this card before with Lubuntu with no problems, but that was when it was installed on a hard drive, not USB flash drive.
Does anyone have any suggestions or advice? Let me know if you need more info.