Safe sleep hangs on my PBG4 1.67 HR

Question

I just installed (myself) a new hard drive (went from the stock 80GB, which was almost full, to a 120GB Western Digital Scorpio WD1200VE). I think, but am not certain, that this problem appeared then (it could also be a coincidence).
When I sleep the PB now, the screen goes dark, however the white LED *stays lit* instead of pulses. I cannot wake the computer. The only thing I can do is force shutdown and restart. When I hold the power key to force shutdown, after a few seconds the LED goes out as I expect. But when I restart, the computer instead seems to wake from safe sleep (fuzzy greyscale window), and all my apps and documents are as they were before. I say "SEEMS to wake" because when I look at the Console log, I see that my PB actually doesn't write the ram contents to the hard drive (i.e., enter safe sleep) until I am pressing the power button to restart; then, one second later it spits it right back out to ram! So, all the time I think I'm "sleeping", it looks like the power is actually on but the screen is dark and the keyboard unresponsive. There is no activity reported in the logs during the "sleep" time, though.
I have so far tried resetting the PMU, and also run Tech Tool Pro4 tests (everything passed). Also, I deleted some plist files having to do with power management I read about here. Nothing has helped. After investigating more, I learned how to set the hibernate mode via Terminal; I set it to "0" (old style sleep), and that works -- the LED pulses and I am truly asleep, and opening the lid or pressing a key wakes the PB. hibernatemode 1 or 3 (both involving safe sleep) present me with the same problem I've described.
This is a tough one, I would like to be able to rely on safe sleep when I need to. Any ideas on the cause or troubleshooting tips are appreciated. Thanks!
1.67Ghz PBG4 "HR"   Mac OS X (10.4.8)   1.5GB ram

Answer 1

Hi MasterG,
Yes, it's strange. However, you have given me a a further clue. I'd already checked the sleep timeout for when the system is idle - it was set at around 10 minutes, I think.
But, following your suggestion, I started looking at all the power options resulting in sleep, and setting them all to "do nothing". I found that changing the option for when the lid is closed from "sleep" to "do nothing" causes the screen to go blank for a second or so, and some disk activity to begin, but the laptop no longer sleeps. Instead, it resumes from where it left off after a few seconds, albeit only to repeat these steps almost immediately.
As a further test, I left the "When lid closed" setting on "sleep" for when the system is running on battery, and on "do nothing" for when it is running on mains. When on mains the system behaves as described above, when on battery it sleeps as I described in my first post (although I had initially thought that the problem didn't happen at all on battery).
So, the problem seems to be something to do with how the machine detects that the lid is closed. Do you know how that's achieved in L40s? Or is there a service manual available for it that might give a clue?
Many thanks,
Rob.