How Do You Read and Understand System Logs

Earlier in the week I posted a question about whether high heat and humidity could be the reason why my iBook laptop keeps suddenly blacking out and shutting down completely. When I start it back up everything seems to be okay, except that the date always goes back to December 1969. I have very little money and wondered if there was anything I could do to resolve the problem on my own.

One person was kind enough to reply that the problem might be a thermal shutdown. I was told to note the time when this happens, then go into Console in applications and check the system log for clues on what might be wrong. Last night I turned on my computer for the first time in several days. I did a new backup, printed out the Console system log, and then the computer blacked out. I started the computer back up and printed out a new system log, without bothering to change the date from the default December 1969 month. My personal iBook Clamshell isn't connected to the Internet (it hasn't been since it was given to me in 2006) so I can't cut and paste the system logs. I'll attempt to type them out as accurately as possible. Can anyone tell me if these logs give any useful information about what may be wrong with my computer?

This log was printed on August 20, 2009, at about 9:25 p.m.:

Mac OS X Version 10.2.8 (Build 6R73)
Sep 2 21:09:30 Diane-Johnsons-Computer WindowServer [174]: CGXDisableUpdate:
Updates disabled by connection 0x5c03 for over 1.000000 seconds

2010-09-02 21:09:30.584 Internet Reminder[325] checkForInternet not implemented
PPPExec(PPP_STATUS) failed: status = 19
PPPExec(PPP_STATUS) failed: status = 19

This log was printed about 10 minutes later, after the laptop blacked out and was turned back on, but before I changed the date from the December 1969 default:

Mac OS X Version 10.2.8 (Build 6R73)
Dec 31 19:07:49 Diane-Johnsons-Computer WindowServer [176]: CGXDisableUpdate:
Updates disabled by connection 0x5c03 for over 1.000000 seconds

1969-12-31 19:07:49.723 Internet Reminder[329] checkForInternet not implemented
PPPExec(PPP_STATUS) failed: status = 19
PPPExec(PPP_STATUS) failed: status = 19
Dec 31 19:08:03 Diane-Johnsons-Computer WindowServer [176]: CGXDisableUpdate:
Updates disabled by connection 0x590f for over 1.000000 seconds

Thank you for any help you can give on what these logs might be trying to tell this very Tech Challenged gal. (Diane Johnson is the person who owned the computer before it was given to me.)