Periodic Mac crashes-- regualr time and day

[MidnightJava]

I've had some periodic crashes for a while now, but recently they've settled into a regular pattern. For the past three Sundays, the Mac crashed at approx 1351 local time. (I verified the time via an app I wrote that writes the current time to a file every minute.) Before that, it crashed at a different time on Sunday, and before that I had a couple crashes on other days. Perhaps there was a different problem before, so I'm going after the Sunday 1351 crash and trying to find the cause.

I've looked at all the periodic tasks that I know about and I don't see anything scheduled for that day and time. I've looked at the pList files for the periodic scripts in /System/Library/LaunchDaemons and nothing executes on that day and time. There are lots of other file sin there, but none seem to be periodic and I didn't check them all, just a few.

I also checked crontab at /etc/crontab and saw only three items that I know about that are not executing weekly or at any time near 1351.

Where else should I look for periodic script settings?

BTW, when the Mac crashes I mean that it hangs. Nothing on the screen, but the CPU seems ot be running (light is on) but the web server and ftp server I run are not responding. I have to power down and back on again to fix it. I'm running OS 10.4.8

 

[symphonix]

You should also have a look at console logs for the time of the crash, using the /Applications/Utilities/Console.app. That will give you a good idea of what was happening at the time of the crash.

 

[MidnightJava]

I should have mentioned that I checked the console logs after previous failures and saw no entries around the time of the crash. For today's incident, the earliest entry in console.log is at 1500 (crash occurred at 1351), and system.log has an entry for 0500, followed by one for 1500.

There are other logs to check, but I need some clues to know which ones. I was hoping to find some cron or initd entry that I could associate with Sunday @ 1351. Spotlight was pretty useless when I searched on crontab; didn't even find the one instance I knew about, and turned up mostly a bunch of c header files.

 

[MidnightJava]

A month later this problem still exists, and I've gathered more data to demonstrate the pattern. The crashes only happen on Sundays, but not every Sunday. In the last 15 weeks there were 6 crashes. There is some uniformity in the time of the crashes, but not always. Here is the time of the crashes in order of occurrence:

1. 13:51
2. 13:51
3. 13:51
(the above three occurred three weeks in a row)
4. 13:06
5. Time unknown (failed to run the time capture program before the crash)
6. 16:05

Surely there is some periodic task that explains these, since they always happen on Sunday. I just don't know Unix very well, so I'm at a loss for how to investigate this any further than I've done so far. Someday I hope to learn Unix in-depth, but I have higher priorities now for the little time I have for technical study. Can someone tell me how I can exhaustively determine what periodic tasks are running on my machine, beyond what I've already done? Or is there some other explanation for Sunday-only crashes besides a periodic task?

Perhaps another clue is that when I reboot the Mac after a crash, in addition to the dialog that offers me the chance to submit the crash report to Apple, the Bluetooth dialog comes up and tells me that the keyboard needs to be re-paired with the computer. But it fails to find the keyboard until I turn the keyboard power switch off and on. Then it pairs successfully; but the same Bluetooth dialog occurs the next time the Mac is booted after a crash.