Just a small follow-up to my previous email: I've just had a look at the hardware, that causes the problem before I've exchanged it with the new one, that now also produce the problem.
This server seems to have the same hardware-setup then the server1, I mentioned the email before, which is not freezing. Here I see the same memory-setup : spdmem0 at iic0 addr 0x50: 4GB DDR3 SDRAM PC3-12800 spdmem1 at iic0 addr 0x52: 4GB DDR3 SDRAM PC3-12800 and no acpipci0 at acpi0 PCI0: 0x00000010 0x00000011 0x000000 which may be produced from the current-kernel.
