Everything runs great on my system, Xbench provides smoking fast results as shown attached. Now when I try to copy large files of around a Gigabyte or more between my main HD (SATA or PATA, I tried both) and either another SATA, another PATA, or a USB HD, the system just locks up, everything is frozen, and the only way to fix this is with a hard reboot.

Anyone have any ideas on where to start to try and figure out what is causing this? I didn't see anything in console so I am just curious on where to start. Is anyone else having the same problem?