Crashes caused by numerous file writes

I've been experiencing an alarming number of system freezes in the last couple of weeks (nothing appears in any of the system log files, but all processes stop dead - everything just freezes).

I've tracked the problem down to certain cron jobs that cause a large number of smallish (~ 100k) files to be created in a single directory, approximately 3 per second or so. I've never had a crash when one of these jobs isn't running; on the other hand, when they do run, the system can be stable for a variable length of time, sometimes only a couple of minutes, sometimes a couple of hours, but eventually a crash comes.

As I've been running these jobs for months with no problems, I'm not sure where I should be looking to identify the root cause. Here are my only thoughts:

1. Hardware failure. The files are being written to a fairly new IDE hard disk (a different parbreastion (ext3) to but the same disk). However, fsck seems happy, and I don't experience disk problems outside the stress conditions described above.

2. Overheating. The weather's hot, my box isn't that well ventilated. Seems a bit unlikely?

Apart from this I'm out of ideas. Can anyone suggest anything to think about?

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