OSX cannot shutdown restart or swicth user


Hi, folks

I have switched from PC half year ago and my experience with OSX is very good so far.

One day I came back from work and my wife told me our imac G5 is freezing,
I took a look and did a shutdown by holding on the power button.

After that it stucked in a blue screen, and I did a few times hold power button as that is my only choose, it was not helping.

Therefore I decide to do the PC way, take out my OSX disk and did a re-install with keeping my previous user profile.

It login ok after that but I notice two issue is happening

1. I cannot switch user by clicking the username in right top corner, and it turns to the color ball forerver.

sometimes it works if u just login but after a good mac use 30 mins, it will not be able to switch user as above described.

2. I no longer can do restart or shutdown from finder
after I click on it, it just do nothing, no color ball, no CPU high, just nothing

However, I can do shutdown from terminal, and sleep and force to quit is working from finder.

I notice shutdown problem is happending after I did a onyx and onyx is able to shutdown mac after did a scan.

3.while I doing update I see some red process hang and update cannot complete, but I am not sure which patch I am updaing.

I have a feeling this is the root of all this three issues, as I kind of remember I was updating before this all happned.

BTW, I am a very heavy BT user, not usre this helps or not.

Following is what I did so far

re-install OSX with keep user profile(twice)
fsck repair
nvram reset
removed com.apple.finder.plis, com.apple.sidebarlists.plist

Someone suggested to delete the folder 'Quickbackstartup' (part of 'speedtools')in the startupitems folder in the Library folder.
However, I cannot find that file.

I am using Imac G5 1.8 10.3

many thanks for viewing my threads
Sorry that I can't help but I have a similar problem...

I was doing a routine Software Update but it crashed and now my IMAC G5 is chasing its own tail during startup. I had to force quit the update after it crashed midway through, it didn't respond, so I restarted the computer by holding the button down but now it never gets beyond the spinning wheel icon on the gray screen to launch Tiger.

I tried holding OPTION on reboot and starting that way to run the Disk Utility but that didn't help. Is there any other forced lauches that people might recommend, or should I just reinstall the system software???

Obviously, having read this thread I am not too keen to reinstall from disk if it is going to result in a similar problem?
if you are BT user like me and all downloads are 75%, u can try to re-intsall but keep ur profile(they will ask), so nothing will be missing.

so far as I see there are a few ppls are seeing samething, and most of them did a update.

dont know why this is happening to only us, but certainly dont wnat to fully reinstall.

I create a new user and same thing so assuming something crashed in system.

I have herad that if software update is crashed, syetem will keep trying to process that, that make sense why we cannot shutdown as it is not finished yet.

Well I am not sure sure as I am newbie in Mac