What is my Ti-book telling me?

Question

Trouble began after my son's visit to a gaming site (via yahoo), if that suggests a possible connection.
History:
- complete freeze while working with Pages (v1.0.2) document.
- restart via power button.
- three chimes/four flashes: "no good banks," according to Article 58183. I don't know what that means. Lots of fish off Georges Banks, though.
- occasionally (or maybe if I hold the power button down too long when trying to start?) there is first one long beep and rapid flashes, then three beeps and four flashes.
- restart from install disk froze, eventually succeded; disk repair reported No Problem.
- restart in single-user mode froze, eventually succeded; fsck -f reported No Problem.
- restarted from external drive, ran full Techtool suites and optimization.
- things seemed ok for awhile.
- three days later, first sign of lingering problem was need to force quit Mail after endless chugging would not resolve Deleting of Junk.
- "Internet connection terminated due to lack of activity." Huh?
- freezing with Pages doc again. Restarts came easily, but first keystroke in doc would freeze. Exported doc to Word; first keystroke would also freeze.
- thought problem may be corrupt Pages pref files (and maybe there are corrupt prefs), or something, but machine froze when trying to eject external drive. May freeze if looked at sideways.
- Disk repair, permission repair, Techtool all ran again, all reported No Problem, or fixed minor problems.
- machine is currently on, finder unfrozen and seemingly available, but clearly unstable.
I'll be grateful for any insights. Thanks!

Answer 1

The three beeps from the Power On Self Test means "bad RAM", which you already know. I didn't find anything more enlightening in a quick search of the Apple Knowledge Base. When the POST fails, you are dead in the water until the problem is resolved since it is the very first step in the boot process.
Since the machine apparently thinks the RAM is bad, despite what the AHT said, and your 512 MB is probably two 256 sticks, I would try removing the upper one, try booting, move the lower one to the upper slot, try booting, and so on until I'd tried both sticks in both slots. If you find a combination that works, then you can try the other stick in that slot. Maybe this will isolate the problem to one stick or slot. If nothing works, I would try to find a friend with a Mac that I could test the RAM sticks in; if neither works in a different machine, i'd have to conclude that they both died at once . . . which would seem pretty unlikely.
If you try this, be gentle with the retaining tabs that hold the RAM sticks in place-- they have been known to break if bent too far. The sticks will pop up when you pull the tabs. You can find illustrated instructions at the PBFixit link above.