Why won't my iMac start?

Question

I couldn't start my iMac a few days ago. Nothing seemed to help...until maybe the 30th time I tried to get it started, it finally started. After that, I had no problems--until last night, when it again refused to start, and again this morning when it still wouldn't start. I tried everything contained in the the bible of iMac maintenance and repair, "Sad Macs, Bombs, and other Disasters," but still it wouldn't start. I was resigned to buying a second-hand computer to tide me over until I bought my new one, when the unexpected happened: it started. I just pushed on the power button as I had already done for perhaps 50 times, and it started,just as it had when the computer was in the bloom of youth.
What are some of the likely reasons for the problem I'm having...sometimes. Is it at all possible that the room temperature might have something to do with it?
A few additional comments: the reset button seemed to have no effect whatsoever. The result for most of those 50 unsuccessful attempts described above was that the Power Button would light up for a fraction of a second and a starting tone would sound, and then the computer would go out. Other times nothing would happen. No light. No sound.
I'm not going to turn off my computer again until I buy the new one. Let me know if that might not be a wise thing to do.

Answer 1

now does your mac turn on but go to a black screen
with colors of vertical lines, then when you
restart
it, it does something different?
No
My iMac will run
fine on hours end when i consistantly use it at
one
time.
So does mine.
but then i go to sleep wake up to find that
it
takes me 10 or 11 times to turn it
on...wait...restart and finally get to the
homescreen. after that its peaches and cream.
You're lucky. It takes me more tries than that. When I said 50, I wasn't kidding. Maybe more than that.
a
buddy of mine told me that it could be the
permissions which repair can be made in the disk
utility. i've tried unplugging my computer for a
while then using it later (i moved 3 hours away
from
home with it next to my lap) and it only took
longer
to get it to the homescreen. i ran a hardware test
and everything is fine.
My computer has now been cleared by TechTool Pro, Disk Warrior, and the program that comes with the computer (Disk Utility?). Unfortunatley, my computer hasn't yet gotten the word, becauee it still doesn't want to start.
the usual advice online or
from mac is to reinstall OS X. it is a software
problem i beleive. i reinstalled OS X, but no
return.
im erasing my hard drive and starting over.
I try to avoid things like that. I don't have enough confidence in my abilities.
i've
lost
hope. by the way is this like anything you where
going through?
No, my problem is just as I've described. The only thing we have in common is that I have no problems during the day, but every morning is another battle.
Are you talking about an iMac G3 CRT?
Yes
You have an
iMac G5 listed as being your computer. Reason I'm
asking is because if you are talking about a G3 CRT
and if you installed OS X on it without updating the
firmware, you need to update the firmware REAL QUICK,
and do not, under any circumstances, reset the PRAM
until after you get the firmware updated.
I didn't trust myself to install the OS X, so I had it done by an Apple authorized computer repair shop. Of course, I've found that "Apple authorized" is no guarantee of good service. I could tell you some stories about one that you probably wouldn't believe. Fortunately for the unknowing public, they went out of business. Oh, as to the FIRMWARE, I checked on it anyway, and I do have the required version.
If you actually have an iMac G5, there is a separate
discussion area for that machine, so disregard the
firmware comment if that is the case.
Going through the starting process is a real pain in the neck, so I'm going to try to keep the computer "awake" tonight by giving it something to do. "Indexing" the Hard Drive seems to take forever, so I'm going to ask it to do that before I go to bed. Maybe that will keep it from shutting itself off.
Oh, one last thing, maybe the Apple Repair Manual would have your answers. Just be careful when you buy it on amazon or elsewhere that your're geting the right manual and that the seller is in America. I wasn't careful, so I now have to wait for it to be delivered from England. Also, it cost me about $17, whereas I'm told that it can be purchased for around $6.