Impossible Tiger install on my imac G4

Question

Hi everybody ! I'm new (well, almost, it's my second post) here, and I've been advised to post a new topic concerning my problem, so here I am...
First of all, let's start with a little explanation (not that small, actually) : I've bought, a year ago from now, an Imac G4 20". It's, in my opinion, one of the most beautiful (if not THE most) computers ever created, and I wanted to get one before there disappearance, with the arrival of the G5 generation. So I bought one (with a really nice discount, because of the new imacs arriving and all...) and thought that I would live happily ever after with it. I had also bought an Ibook G4 14" 1,33Ghz, a month before.
Everything went quite fine (a freeze when running limewire and mplayer at the same time but that might have been because of the 256 Mo of memory) till I bought Tiger. I bought the complete system, not an update version with a computer or something like that. Anyway, I bought Tiger and the troubles began. I started with a simple upgrade, from 10.3.9 to 10.4 (something that had always worked perfectly fine for me on all my macs from OS 9.1 to Panther).
Once the installation process completed, the imac restarted as usual, all by itself, and after a few seconds, stopped on a light blue screen (I say light as it seemed to me that it was lighter than the usual blue background behind the loading sequence) and stood like that. After a few minutes (like 10 or something) I decided to reboot, in safe mode (reboot button + shift) and after a really long startup sequence (which, as I learned later, was normal). It worked, I could use my computer, minus all the disabled options. So I thought that it was certainly a problem of compatibility with an application or something plugged in the computer. So I checked the disk and repaired what had to be repaired, saved all my data on my external FW HD, and tried to :
- restart and zap the pram : same light blue screen, safe mode only
- format the HD : same result
- custom format of the HD (9 times) : same result
- start again after having unplugged all the non apple stuff (ethernet link, HP printer, trackball) : same result
As I didn't want to be stuck with the safe mode (which is really useful, don't misunderstand me, but when you buy a complete system, you're supposed to be able to use it) till the end of times, I called the hotline, and after having once again tried all of the staff mentionned above, the guy in charge of my case sent me a small app, which, once run on my imac (still in safe mode) produced a file, listing obscure and unreadable (well, for me anyway... lol) datas, file that I sent back.
After a week or two of intense waiting, I decided to call back . The guy seemed to have lost my file (breathe... breathe... breathe...). He called me back after a few days to tell me that the datas had been analysed and the conclusion was chathat my imac could not get Tiger, unless something was changed in the computer itself (and it was not the memory, as I had only the 256 Mo, factory installed). The surgical act could apparently be done in an apple center, but I had no mean of transport at that time , and was really starting to get tired about all this. The guy told me that I was not the first one to report this bug, and that it seemed to concern certain models of imacs G4 20" only. Then, he tried to sell me an apple care, which I refused. So I reinstalled panther, which works perfectly fine and installed Tiger on my ibook (something that I originally didn't want to do) which works perfectly fine too.
I forgot to mention that apple sent me, in the early days of this situation, another copy of Tiger, as they thought that the problem might have come from the DVD itself. As I used the DVD I bought on my ibook later, I guess it's not the case. So I forgot all about that till I found this forum (I have exposed my problem on the french forum of macgeneration.com but without any success). So if someone knows about this particular issue, or even has experienced it (as it seems to concern imac G4 20" only) please help me... lol and thank you for having read me till the end.
PS : And please forget the mistakes. My english is not what it used to be.

Answer 1

The problem may be that you only have 256 Mo of RAM. That's the bare minimum, and many have found that it is difficult to do anything but word processing with that minimum. If for any reason even a small part of that RAM is damaged, the installation may not work properly. I strongly recommend going to http://www.crucial.com/ and upgrade to at least 512 Mo (or MB, which is the U.S. term for the same) of RAM if you still desire to upgrade to Tiger for some of the features it offers, or a program you know only to run in Tiger. And when you do, backup your data, and be sure you have plenty of hard disk space available and try to Archive and Install as described below:
http://docs.info.apple.com/article.html?artnum=107120
P.S. Your English is very good and clear. Keep up the good work!