Wow, I think we might fix this.
Open Activity Monitor, Show:>All Processes, sort on CPU%, see if anything using too much CPU% when this happens, click on Memory tab, do you have many Pageouts?
Open Console in Utilities & see if there are any clues or repeating messages when this happens.
One way to test is to Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, Test for problem in Safe Mode...
PS. Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive
Reboot, test again.
If it only does it in Regular Boot, then it could be some hardware problem like Video card, (Quartz is turned off in Safe Mode), or Airport, or 3rd party add-on, Check System Preferences>Accounts>Login Items window to see if it or something relevant is listed.
Check the System Preferences>Other Row, for 3rd party Pref Panes.
Also look in these if they exist, some are invisible...
>Open Activity Monitor, Show:>All Processes, sort on CPU%, see if anything using too much CPU% when this happens, click on Memory tab, do you have many Pageouts?
How can excessive CPU be identified? ScanPro is in red and "not responding," which i already know. I dont understand Activity Monitor.
Pageouts were in the hundreds of thousands when I first looked. After some scan attempts, it is zero. I dont even know what a pageout is.
>Check the System Preferences>Other Row, for 3rd party Pref Panes.
No "Other" row.
> Also look in these if they exist, some are invisible...
Spotlight displayed some of my document files as well as other files whose use I dont know.
Do various printer bugs, when its not linked to my G4, mean that printer is broken? Power button fails to shut printer; power cable must be pulled from power to shut printer. When power cable connected to power, power light might be on. Lights blink erratically regardless of which buttons I push. Cartridge moves randomly or starts to move. If printer broken, repair cost probably more than new printer (Staples has something for $80.) If printer broken, are there any simple repairs I might do even if repair may destroy something?
If this is without connected to the Mac, it sure sounds like the Printer is broken.
I doubt there's anyway to fix the printer for less than 5 times the cost of a new one.
Or, maybe use HP resources to deal with the printer.
It sounds like something is hung up in the printer's processor itself.
All HP advice failed. Their diagnostic program is PC-only even tho they have software for Mac. The last "fix," disconnecting power cord from printer and wall, stopped printer Setup Asst from consistently recognizing printer and stopped scan program (ScanPro) from even failed scan. Ie, "New Scan" button now dimmed. I believe you are right about bad printer processor. Is there anything I, a non-techie, can do to the processor? Maybe hit it a few times with a hammer?
Would using my iMac to work printer help?
Would using my iMac to work printer help?
That would be the next logical troubleshooting step.
I have had some of the HP processes get wrapped around the axle on one or another devices, usually resulting in HP Device manager being unable to see, for instance, the AIO connected to the machine. The usual fix for that has been a reboot, since logging out and back in didn't seem to help at all.
Just did a little "Science Fair" experiment, as I found that the AIO was not showing up in the HP Device Manager Device Chooser window. There is a process hpdot4d which apparently has something to do with the problem. There were actually two instantiations of the process. I killed the older one using Activity Monitor, which didn't help, but killing the newer one (higher Process ID) did allow the Device Chooser to see the AIO. Eventually, after further review, it seems that the instantiation owned by root is the one that needs to be killed to bring things more or less back to normal.
How could another computer cause a printer which is erratic when not linked to a computer to work correctly?
My G4 has no hpdot4d. Of 4 hp processes, only hpusbmond has a root user. Should I "quit process" for it? I know so little about Activity Monitor that I must ask if that process can be restarted. Further, if its a bad process,it must still be a needed one or it would not be there. So if I quit it, what needed process would stop? How could printer function w/o it?
I just noticed that MyDSC (I am user. WindowServer  is parent process) is not responding. I have no idea what this is or means or if its importantly related to my printer bugs.
Occasionally hpdot4d is very briefly displayed in Activity Monitor! Once it was listed twice. Why doesnt it display all the time?! What demon have I offended and how do I appease it?
In HP Setup Asst, my printer briefly displays. In HP AIO Device Chooser, my printer eventually displayed. And other things. This all seems consistent with an intermittently failing printer processor. Or a demon. Intermittent electrical problems in cars are very difficult to identify.
One HP process is HPIO Trap Monito. This is one letter away from a Mohito. Im thirsty from all this analysis. Im going to the Ebbtide. Good luck with my questions. I'll have a drink in your honor.