The computer locks up / freezes randomly throughout the benchmarks and I have to reset the computer - no error messages come up, it just hangs. During normal Office and internet browsing, system hangs very rarely. My configuration is as follows: AMD Athlon 2400+ (Thorougbred) CoolerMaster heatsink 512MB Kingston RAM DDR 400 (1 stick only) Gigabyte VT600 1394 Motherboard Gigabyte Raedon 9250 128MB Soundblaster Live Wireless NIC Antech trupower 550W power supply - no major voltage fluctuations Thermaltake Xaser 3 case (6 fans excellent cooling) I have tried the following: Checked CPU temperature - it is between 40 to 50 Celcius Run Memtest86 overnight - 18 passes over 8 hours with no errors Checked for hardware conflicts - none DIabled fastwrites in BIOS and winXP, and disabled non-essential onboard devices such as NIC, firewire and SATA. I have put a Thermaltake Spirit fan on Northbridge and fan on passively cooled graphics card heatsink makes no difference I have removed all cards except for graphics - no difference Used latest VIA and ATI drivers (including Omega) - no difference Clean installed Windows XP with only latest VIA and graphics drivers and run benchmarks - no difference Also put in friends GForce2 graphics card with latest Nvidia drivers - no difference My friends Intel based system with Nvidia 5200 video card and YumCha 500 Watt power supply runs through benchmarks without any sweat. This is driving me insane. Do I have a bad mobo - can anyone please help???