Computer clock resets to 1969. PRAM battery probably not the issue.

Question

I have a PowerMac G4 mirrored doors computer running Tiger 10.4.11 that occasionally starts up with that error message saying: "Your computer's clock is set to a date before March 24th, 2001. This may cause some applications to behave erratically."
I know all about resetting the PRAM, resetting the NVRAM, and replacing a weak, or expired battery. I've read the relevant posts on the subject, in which well-intentioned guides say that the problem is "usually" or "generally" related to the PRAM battery. Well, I wish it could be that simple, because I have already had a new battery installed, and the problem continues. It is intermittent; it's been occurring for about six months now; and it persists.
I seek technical assistance and successful, problem-solving suggestions that go beyond merely suggesting that I zap the PRAM or replace the battery.
If there are potential SOFTWARE problems, please direct me to those potentially damaged files. None of the disk utilities that I have used—including Disk Warrior, TechTool Pro, OnyX, Cocktail, or Drive Genius— find anything wrong with my hard drive or the files on it. No corrupted resources are reported. Additionally, Intego's Virus Barrier finds no infected files either.
However, a FileBuddy search of files modified before 3/25/2001 finds several dozen files with improbable dates of 12/31/1969 or 1/1/1970. Fewer files dated 12/31/1969 occur after I go to the Date/Time preferences pane and reset the clock to the current date/time and then restart my computer, especially in regards to system-related files. Nonetheless, several dozen files with a 12/31/1969 still remain, even after the date/time reset and the system restart.
I do not know if any of those pre-historic files are playing a role in this chronic problem, so I offer that information for the technically more astute to ponder upon and factor in to any solutions which might be offered. I have read posts where someone might suggest a re-install of Tiger, but the original poster almost always reports that re-installing Tiger did not eliminate problem, so I would prefer suggestions that rely on a scalpel rather than a sledge hammer.
If someone suspects that there may be hardware problem, I would like to hear theories along that line, too, although I am unlikely to consider gutting the hardware items just to retain the attractive computer case. Even though I do have other computers (an iMac G5 and a MacBook Pro), the PowerMac G4 is my preferred workhorse, and it is the only one configured to run Final Cut Pro (version 4.5; I can't afford to upgrade now), so I want to keep it functional without a major investment into an older machine.
When the computer clock problem first reared its irritating head several months ago, it was accompanied with kernel crashes that turned out to be related to the nVidia video card. I brought the machine in to a local shop, because it was refusing to power on. They installed a new battery to replace the original, probably weak original battery, and they replaced the probably defective nVidia video card with a used nVidia card I found on eBay. The shop also claimed that I needed to replace the motherboard and the power supply to ensure that the G4 would power on and that it would present a desktop without the warning message about the computer clock being set to 12/31/1969.
I decided to reject their assessment, since the whole repair job would have amounted to about $1,100. It seemed like an excessive solution. Since taking the G4 back about three months ago with only the new battery and the replacement video card installed, the computer has powered on every single time without fail, which, to my non-technician mind, would appear to indicate that the power supply is OK. However, I do still get an occasional warning about the computer clock being set to a date before March 24th, 2001.
I do not have the technical expertise or repair knowledge to know if the problem is hardware-related, software-related, power supply-related, or a complex interaction between all of them. If someone can suggest a permanent fix to eliminate the computer clock error problem WITHOUT requiring me to make a major investment in repairing or replacing hardware components, that would be ideal. On the other hand, if this clock problem is merely is an irritant, but not a sign of something more serious or expensive, then I am willing to live with it and get around the problem by going through the steps of resetting the clock when required and then restarting the computer with a correctly set clock.
My main goal, of course, is to have a reliable, stable computer. If it costs too much to eliminate the computer clock irritation on a permanent basis, then I am willing to live with the problem, as long as its presence does not disrupt my work flow. In that case, I would appreciate it if someone could explain what might be going on, so that I know what to expect and what to do about it.
I hope this is sufficient information with which to make a diagnosis and recommendation. If not, ask for more. Thanks.
bowlerboy

Answer 1

Short answer =
5) Upon reboot after re-connection and re-start, the Date & Time shows...
a) in the Date & Time pane: 12/31/1969 at 7:00 PM, and counting
b) in the Finder's menu bar: 7:00 PM, and counting
What do the results of this test tell you? Is this a software or a hardware problem?
======================================================================
Long answer =
Thanks, BDAqua, for offering your help. I'm not exactly new to these forums, but somehow my previous contributions have all been wiped out, so I've restarted under a new account name.
I've had my G4 MDD for five years, and it's always been quite stable for me, so I'm not quite sure that this model is "cantankerous." I do find the computer clock error message irritating, though, so it would be nice to know the source of the problem and its permanent solution.
Since my original posting, I elected not to Shut Down the G4 to see what would happen. It functioned just fine since then, allowing me to create some short Final Cut Pro movies as Christmas presents to family members. With one exception, all other applications also functioned without problems. The only problem I'm encountering has to do with H-P Photosmart Studio, an application bundled with the HP All-in-one model C7280. It will not settle down to work, forcing me to Force Quit it every time. Since that app works fine on my iMac G5, I decided to trouble-shoot it by reinstalling the HP software, a process that requires me to Shut Down. (If possible, I want to see if the problem is with the HP software, or with Tiger on my G4.)
However, before I can get even get to trouble-shooting the HP Photosmart, the G4 gives me that computer clock error upon re-boot. In the past, the Date & Time error message has appeared upon a cold reboot, no matter whether I had reset the Date & Time in the preference pane via the Network clock or manually. However, I never conducted my tests in conjunction with disconnecting the A/C power cable. So, I decided to try the the test you suggested. Here are my observations and the results of the test.
1) Upon Shut Down, cool down, and restart, I get the computer clock error message mentioned at the beginning of my original post, telling me that my clock is set to a earlier date.
2) When I open the Date & Time preferences pane, however, the date and time shown there (as well as on the Finder's menu bar) is current.
3) The Network setting was ON, so, to comply with this test, I unchecked the "Set date & time automatically" box. I do not need to reset date and time manually, because, as I mentioned they ARE set correctly, even though the message I got upon restart said that they are not. (If memory serves me correctly, though, the Date & Time panel would actually show 12/31/69 as the computer clock's read-out, so this discrepancy is somehow connected to this problem. )
4) I shut down the G4 for 2 hours, and I disconnected all cables and plugs to it, including A/C power.
5) Upon reboot after re-connection and re-start, the Date & Time shows...
a) in the Date & Time pane: 12/31/1969 at 7:00 PM, and counting
b) in the Finder's menu bar: 7:00 PM, and counting.
6) I take screen captures of the error message and the menu bar: both .PNG files are time-stamped as of 12/31/1969 at around 7:01 PM.
7) I will now reset the clock to the current Date and Time by turning the Network time feature back on, so I can get on with my work while the trouble-shooting process continues.
What do the results of this test tell you? Is this a software or a hardware problem?
If it's a software problem, then should I do I clean install of Tiger? If I do that, is there any evidence that a clean install will do any good to eradicate the problem?
On the other hand, if this is a hardware issue, is it contained to merely being an irritant that I can fix merely by adjusting the Date & Time whenever the problem occurs (which I can live with, as long as the system is stable after that fix), or is this error message regarding a sign of something more ominous failing on the motherboard?
bowlerboy