I think I fix it. I was using the forcedeth from 10.5.2 zephyroth release. Than I change for this: http://forum.insanelymac.com/index.php?showtopic=12933

I think the problem its gone. I did run Azureus at 60-70kb/s for about 20 minutes and that was ok. I´m gonna try another donwload with more speed (90K or more) and see what happens. I will give you guys my report.