Originally Posted by david_e
OK. I'll need some time... I will report after the upgrade.
I have flashed the new BIOS image from the BART P.E. "Windows Live CD". It was four days ago, I didn't had any problem since then: I usually got a crash after five hour of uptime using beryl, now I went as far as 10 hour of uptime without any problem, stressing the graphical effects a lot, so it seems that flashing the BIOS did it.
Thanks netllama for your help.