...
That explains everything. Thank You Kano! I really appreciate it. And as for Antminer's S2 I removed hash boards with no result but I think I know what is going on: PSU fan is not working and this might cause an random shutdowns. But I'll replace the fan and hopefully everything will be ok.
Besides I would like to ask about S2 new firmare: could upgrade change productivity and give some better results with mining?
And thx for explanaition about the pools like BTC Guild and Eligius. Many times I was wondering which pool should I choose

EDIT: Hmmmm....I can't download latest firmware. Is there any other way? I would like to try it because there are few changes which are interesting

Odd - is github not working for you?
I've also got it here:
http://198.136.28.106/initramfs.bin.SD-Kano-20150524073531.tar---
There was a datacentre issue for 2 minutes, 40 mins ago and some people may have lost their connection (but reconnected shortly after)
I did, but that may not have affected too many other people, since I'm way over here in Aus

(it affected my access to 2 on my servers for 2 minutes)
---
Edit: forgot to add ... 3 hours ago ...
Payouts 361153 and 361170 sent
8a9ece84f95fcd6769c49f60ed2ce43a7c5e3b5fd2383f2b0ad819306a588faf
b92b2269cd69fbb8c704f2a61f8c36513651f262a06451fc06e479a81cf00823
and confirmed