I suggest you unplug the USB Hub, remove the second hard drive, and use one only. And check that all the connectors of the IDE cables which are plugged in : in the hard drive, in the ATAPI / Cdrom drives are either the last one on the cable or anyhow be sure none of the last connectors of each one hangs out. (It should not act as an antenna).
I have not seen anything very significant in your /var/log/messages at the moment, except that there is a USB hub and several internal peripherals connected. Two hard drives at same time might be too much for the power supply unit. You also could try another PSU if you can have one.
Else, I have gone to the Via website and looked for a new bios for your machine : none available, the eldest are for P4 machines. :-/
I have seen little things in the "messages" in fact, but before saying anything I would like to be sure it is a part of the "messages" taken just after a reboot which occurred after a freeze.
While I'm here, instead of doing a hard reboot with the button, you may want to use the magic keys:
Alt+Shift with the left hand, and press at same time the "PrintScr" key with the right hand, hold all and then one after the other, with another finger do "R+E+I+S+U+K+B".
This has for name "SysRq" : system rescue http://en.wikipedia.org/wiki/SysRq