It stopped working after a few minutes

[gllobet@gmail.com]

I have installed the last version of the software (1.0.138). Things were working fine at the beginning but after a few minutes the screen turned into gibberish. I attach a picture of what I mean.
Unplugging and plugging it again did not help, nor did restarting the service or rebooting the computer.
My configuration is the following:

- Dell XPS13 (first generation)
- Ubuntu 15.04 (kernel 3.19.0.30)
- Targus ACP71
- Monitor Dell U2312

Any ideas of what may have gone wrong? I did not change the configuration in any way, as far as I know...