I've had installed several different GNU/Linux distros that worked very well and fast in this computer, a desktop. Recently I've installed Debian, it was slow, sensibly slower than any other distros. I did already use Debian on this machine having a normal speed. I recall Debian being the fastest distro I've ever used, and that was indeed strange, the turning point to change to Ubuntu was when I started to get black screens that wouldn't go away, the keyboard with lights off, not being possible turning on numlock or CTRL+ALT+F1-2,3,etc. Only rebooting could make the problem go away. So I installed Ubuntu, thing that was complicated, several times I would get a black screen or blank screen, but I got it through after trying several times. The problem persisted, and I sometimes get this problem.

The problem is much more prevalent on Ubuntu. It occourred with its Live USB thing many times. It occourred in Debian too, but much less.

Working logs:
http://pastebin.com/dhDbJ7LM
http://pastebin.com/qPHhstrb