Thx for this thread. It solves my problem in the way that i know it is was problem of my 6GB Ram. Now i'm waiting for the threadstarter to tell me which file(s) i should take und until he tells me my PC runs with 2 GB Ram. With 2GB Ram inside erverythings works fine at the moment.

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Snow Leopard 10.6.4
Gigabyte GA-P55-USB3, Intel Core i5 650 - 3,20 GHz, Realtek ALC892, Kingston 4GB, RTL8111E chip, Nvidia GT240 Silent, Maxtor (500GB), Samsung (1,5TB), LG DVD, Samsung DVD Burner

Snow Leopard 10.6.4
Gigabyte GA-965P-DS3, Intel Core 2 Duo E6320 1,8 GHz, Realtek ALC883, Marvel 8056 Gigabit, 2048MB-KIT G-Skill PC6400/800,CL 5, 4096MB-KIT G-Skill PC8000/1000,CL 5, XFX GeForce 8800GTS 640MB DDR3, WD Caviar (500GB), Samsung SH-D162C (500GB), Samsung DVD