Same problem on a desktop running AMD FX(tm)-6350 Six-Core Processor and
Linux blackie2 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
I was able to C-A-F1 and get a terminal window where I ran service mdm stop;service mdm start and got it working again.
Same problem on a desktop running AMD FX(tm)-6350 Six-Core Processor and
Linux blackie2 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
I was able to C-A-F1 and get a terminal window where I ran service mdm stop;service mdm start and got it working again.