Intermittent black screens

Hi to you all !
I discovered GSB from the last humble bundle, and I’m having a lot of fun with it. I’m playing under Xubuntu 11.10, open source gallium driver from xorg-edgers (old radeon ATI x550) : it’s running quite smoothly except for that :
Intermittent black screens during gameplay. These black screens lasts less than 1 sec, but are quite frequent. Theses black screens also come when I’m scrolling (and lasts as long as I scroll).
I guess you can’t help me with so little information, so is there any log file somewhere or maybe a terminal command to retrieve this log file and post the results here ?
Thanks a lot !

I think it’s a problem from Gallium ATI driver. I have the same problem with my old notebook with ATI and Gallium too.

Ah ! Damned !
'Guess it’s settled then. I don’t think I will see the problem solved anytime soon. It’s not that bad, since I can still play the game.
Thank you for your help !
PS : do you know any command or log script I can use for the game ?