Came into work this morning, and our box running Red Hat Professional Workstation was frozen, just a few of the keyboard LEDs blinking.

I looked through the log files, and it looks like it froze up while it was doing a cron job. The cron job runs nightly and involves tarring some dirs, gzipping the tars, and copying those a zip drive. This cron file has been in place and untouched for about a year now, and has never caused any problems, so I hesitate to think it had anything to do with that. I do know that it froze during the tar portion of the cron job, since the tar file was incomplete. I ran the backup script, and everything backupped fine, which makes me think even less that it was the cron job.

We've had occasional freezes like this before, sometimes in the middle of the night, once in a while during the day. Usually the log files don't tell me anything useful(that I know of).

What can I do in the future to help determine why this is happening, so I can then go on and prevent it from happening?

Welcome to intermittent problem Heck. All sysadmins end up here from time to time. The key here is to keep doing what you've already started to do: look for patterns in the failures. Eventually you will find the HW or SW components that are involved.
If possible I would arrange for some downtime on the box and run a CPU burn test, a memory test, and a nondestructive disk test. Stress the hardware and see if it breaks. That's a good first step to isolating the problem.

DT

I just had another complete system freeze. Went to open a folder (using nautlius) and the entire system froze. Couldn't telnet/ssh in, although I could still ping the system.

I doubt its the hard drive. I recently upgraded the system to RAID-1. I'm using 2 new hard drives for this, old one is sitting around here somewhere. Had the freezing with both the old and the new drives, although it is possible to have multiple bad drives.

What are the best tools for the CPU burn test, memory test, and disk test?

Thanks