Coming from a Windows background, I have no idea how to troubleshoot
Linux.  It's a Cent OS 5.1 Server with GUI install on the following
hardware:

I'm running a P4 3.0 GHz, 1GB RAM, 3 hard drives: IDE 160GB for OS,
boot, swap.  There are two 1TB SATA drives for MySQL.  The hardware
seems sound as it passes UltraX diagnostics boot CD (test CPU, RAM,
drives, motherboard chips).  It's on some kind of whitebox w/ ASROCK
board put together by General Nano.

I installed the updates Cent OS recommends right away with the built
in updater. The OS seems to freeze and becomes unpingable and the box
needs a hard reset.  my user might be doing something in My SQL when
this happens.

Any general troubleshooting advice?  Are there logs or dumps to
analyze?  I'm pretty green Linux-wise.