Machine locks up unexpectedly, questions about cryptic kernel logs
 

Recently, my Linux server (web, email, ftp, etc) has been "acting up" and has actually locked up a few times (monitor is dark from powersave, but won't come back on, and keyboard doesn't respond). Checking the kernel logs (/var/log/messages), I see this quite often:

Node 0 DMA per-cpu:
cpu 0 hot: low 2, high 6, batch 1
cpu 0 cold: low 0, high 2, batch 1
cpu 1 hot: low 2, high 6, batch 1
cpu 1 cold: low 0, high 2, batch 1
Node 0 Normal per-cpu:
cpu 0 hot: low 62, high 186, batch 31
cpu 0 cold: low 0, high 62, batch 31
cpu 1 hot: low 62, high 186, batch 31
cpu 1 cold: low 0, high 62, batch 31
Node 0 NighMem per-cpu: empty

I also see this frequently:
Out of memory: killed process xxxx (httpd2-prefork)

Should I be concerned about the CPU messages, and what is going on with apache?

The machine is an EMT64 3.4 GHz, 1 GB Ram, with 160 GB SATA RAID Level 1 (via 3Ware/AMCC Escalade).

What else should I be checking to determine why my server keeps locking up? This is a production server, so the concern is very big!

Thanks in advance...