Hello, I have this problem - I have installation of Xen and Centos 5 (all RPMs are from Centos repositories). I have several DomU virtual machines running on this machine. When I try to copy some bigger amount of data from another physical computer to Dom0/DomU on this machine, the network freezes. The link is still up, I can see that the connection really links on the switch, but nothing is received or sent to the network. I tried to stop all the DomUs, stop the network, unload the network drivers from memory and loading them again and starting the network, but the problem persists. Only reboot solves the problem. Sometimes the amount of data have to be around gigabytes (last time it was 10GB), sometimes 500MB is enough to stop the network... I also tried to change the NIC, but the behavior is the same. Btw. logs don't say anything :-/ Any idea ? Thank you very much ! Vladimir PS: this is the output of my lspci: 00:00.0 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:00.1 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:00.2 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:00.3 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:00.4 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:00.7 Host bridge: VIA Technologies, Inc. K8T800Pro Host Bridge 00:01.0 PCI bridge: VIA Technologies, Inc. VT8237 PCI bridge [K8T800/K8T890 South] 00:05.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) 00:0b.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5705 Gigabit Ethernet (rev 03) 00:0f.0 RAID bus controller: VIA Technologies, Inc. VIA VT6420 SATA RAID Controller (rev 80) 00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06) 00:10.0 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81) 00:10.1 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81) 00:10.2 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81) 00:10.3 USB Controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81) 00:10.4 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 86) 00:11.0 ISA bridge: VIA Technologies, Inc. VT8237 ISA bridge [KT600/K8T800/K8T890 South] 00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235/8237 AC97 Audio Controller (rev 60) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 00:19.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:19.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:19.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:19.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 01:00.0 VGA compatible controller: nVidia Corporation NV15 [GeForce2 GTS/Pro] (rev a4) output of uname -a: Linux hydra 2.6.18-194.11.4.el5xen #1 SMP Tue Sep 21 05:40:24 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux