You could try to force the resolution using command line parameters. I'm not sure how to do that in Ubuntu though (I'm not a Linux user myself). For example:
-screen-fullscreen 0 -screen-width 1920 -screen-height 1080
Perhaps running it in a window (instead of fullscreen) will help, perhaps not.
Sounds like it some problem with the connection itself. Perhaps it has to do with the video drivers. Does it show the computer desktop properly when you are not running Freerider?