Closure
 

After much hair-pulling and pestering of the wonderful folk on this board, I've decided to buy a Mini as standby, soldier on with the PowerBook till the video dies on me, then get it to Preowned for repairs.

Thank you tlarkin. I can't tell you how valuable your voice and experience are for me, and for this group. Hardware tends to be a dark and mysterious area for many of us, and sane counsel makes the difference between response and panic. Thank you again, as also to Carlos, voldenuit, hayne, and trevor. I am forever in your debt.

My video is crazy too
 

I also have a similar video problem, and looking at your screenshot and described behavior, I think it is the same.

The problem has been intermittent for my Titanium PB G4 1Ghz, 64VRAM for about a year now and I think the problem is the VRAM. My evidence comes from the system profiler. After rebooting and rebooting, I can usually get a normal screen. When it is normal, and I look at the system profiler graphics section, it reports 32MB of total memory. This leads me to believe that half of my VRAM is bad. I wish there were some way to disable the defective VRAM.

When the display is in crazy mode (mangled blocks, lines etc.) profiler always reports 64MB VRAM.

From what I've read, since VRAM is soldered to the logic board, the only solution is to replace the devective board. The 1 Ghz is in short supply on Ebay, so they are pricey. A working board through a retailer will probably be double what you can find it for on Ebay.

software problem?
 

My Powerbook screen started to act weird with 10.4 from time to time as well. The center starts to get really bright and white or I see a login window on top of the actual desktop. The computer is not responding anymore in that mode. However it recovers for a few seconds when put to sleep - which is enough time to reboot. Rebooting usually makes the system stable for some time enough to correct prefrences and delete all caches. After that the Powerbook works fine for a few weeks/month.

So, the usual maintenance jobs seems to solve the problem - at least for some time.
t.

Display fixed, but may melt before I enjoy it!
 

Well, this had a happy ending, sort of. Preowned did the job for $369, which included a new battery and, since they misplaced my power supply, a new power brick.

So thank you, tlarkin, for pointing me to them. It was a logistics challenge to get the machine from Asia to the US, but since I travelled there myself, bringing it back was a cinch.

There's one problem I wish someone would help me with. The machine is running really hot since it came back. (Trust me to notice only when I am 10,000 miles away!) As I type, my wrist is hot to the touch, and Temperature Monitor is showing 68 celsius (154 fahrenheit). So do you think they forgot to connect the fan? :-(

Either that or they didn't install the heat-pipe properly.
You can hear the fan kick in when the temperature rises under load.

Hopefully you'll be able to get it fixed easily.

if you have the hardware test cd you can sometimes reset thermal calibration from that disk. If not reset the nvram and pram and the PMU and that may also recalibrate the fans/cooling.

If all else fails contact the repair center they are usually understanding people.

tlarkin, I tried the hardware test CD, but found no provision for thermal recalibration. However, I ran the ASD, and the fans as well as the heat figures ran okay (correction: they checked out okay, still no idea if the fans are actually running or if the test can miss this).

I can't hear the fan, though. But that could be simply because I have a noisy house, with two kids and two dogs. I'll listen really carefully tonight and report.

I'll eventually call Preowned, but there's no way I can send the machine back to them. I'll eventually have to ask Apple here to take a look. Sigh...

Seems like I had the same problem recently. It turned out to be the a broken logicboard, i.e. the end of my PowerBook 15"... :

http://forums.macosxhints.com/showthread.php?t=72580