Um...Micromat still thinks you need 15% free (unless they've changed their minds in the last year or so). See:
http://www.micromat.com/index.php?option=c...&id=764#764 (and also see the "Why Defrag" link in the post) And has the way Tiger/Leopard handled swap files changed any?
Also, in order for Virtual Memory in OS X to work correctly (again according to Micromat) there should be 4X the amount of installed RAM.
Anyway - it's indeed possible that this is an (intermittent) hardware issue as I noted above, and it may or may not show up on the Hardware test.
There ARE issues with the 17" Powerbook screens - that is well documented, though Apple has refused to acknowledge it - but usually the lines appear and continue to get worse, not appear, then disappear for weeks. So, not sure if this is related or not. A few things that those posting on the Apple forums have noted (including that it is NOT the video RAM):
QUOTE
maybe that's important for the records (e.g. the apple guys reading this discussion), but i guess every user here with a defect screen has already tried this:
- capturing a screenshot shows no defects on the resulting image (shift-cmd-3) -> the video memory is not affected
- the same is when connecting to an external display, no visible defects on the external screen (both in mirrored and extended desktop mode), the defect on the built-in screen stays
- the lines on the built-in display stay in their position even when changing the screen resolution
- the lines are visible from the 1st second the screen comes on when booting until the display goes to sleep or the computer shuts down
- the lines are visible no matter which user logs in, the lines are ALWAYS there
- the lines stay there no matter at what angle i open the display -> no weak/loose contact