I don't think anyone has ever claimed Ubuntu to be robust. RHEL and Debian sure, but not Ubuntu. The *buntus are especially bad since they don't get a lot of love.
I thought it might be something to do with the video card, but southern island cards look like they are supported well. (
http://www.x.org/wiki/RadeonFeature/)
Screenshot #2 suggests it's something USB related. Try unplugging everything except a mouse and keyboard. I'm suspicious of the TP-Link wifi adapter.
Try booting the desktop with Finnix (
http://www.finnix.org/). It's a much more pared down Linux, it boots to a command line, compared to Ubuntu or anything that boots a GUI. It should give you a better idea where things are failing.
I would also suggest booting from a flash drive. A 1-2GB flash drive is more then enough space for Finnix, and the flash drive can be repurposed when you're done.
cheesyking wrote:The reason it does different things on different boots could (and I'm guessing here as I don't really know anything about systemd yet) be because systemd doesn't boot the system in a deterministic way (not sure if I've used the right term there but as I understand it things don't always happen in the same order when systemd initialises the OS, that right?).
Systemd launches everything in parallel, and it satisfies service dependencies queue any communications between services. Service A may depend on service B, but service B may take a long time to load. Systemd tells service A service B is functional while it waits for service B to become operational. When service B finally comes online, systemd delivers the backlog of messages from service A. If this sounds like a recipe for random service errors, that's because it is.