Screen flickers in Lubuntu 14.10 Final Beta

[Doctor Jellyface]

I never had this problem before. I just installed a fresh Lubuntu 
install using LVM. I installed the Lubuntu 14.10 Final Beta, cuase in 
14.10 the xfce4-power-manager systemd (logind) integration is fixed, so 
I can finally put it to sleep normally.

Everything went fine, except this: the screen started to flicker. I just 
see lines - 1 pixel high, varied in length, usually white - across the 
screen. They're really annoying. And the worst part is that I never saw 
something like this on my laptop before.

My system is fully updated. Main server.

Also, a little bug: the xfce4-power-manager fails to lock the screen on 
lid close, even if it is set to lock it. I know how to fix it, but it's 
a kind of a hack - symlinking lxlock as xflock in /usr/bin. Can this be 
fixed normally?

Note: I would have made a bug report, but I don't know where, or how.

Thanks.

--
Juraj Fiala <doctorjellyface at riseup.net>