I burned one cd successfully, but then the next three didn't work.

Question

I just bought my make about a month and a half ago, and up till now there haven't been very many problems. I don't know much about computers...or common mac problems, so I was hoping to get some insight before I call the apple support people. Previously, I have watched a lot of dvds, listened to cds and burned a couple of cds with no problems.
However, last night I started having some issues with it. I burned one cd-r (the same sony brand ones that i always use) and it worked fine. Then I tried to make a second copy and everything was fine until the end of the burning cycle, when it unexpectedly ejected ("the attempt to burn a disc failed. The device failed to respond properly, unable to recover or retry")while it was finishing. Thinking it might just be a faulty disk in the pack, I tried another...same problem. Then I went through the apple troubleshooting guide and I inserted the installation disk that comes with the iMac at there suggestion, but then the cd didn't appear on my desktop and thus wouldn't eject. I had to restart my iMac it later appears. Then I tried one more disk and again it failed and ejected during the "finishing" of the burn. And I might be imagining things, but lately I have been noticing that my drive has gotten quite loud when I insert any type of disk into my drive.
This doesn't seem normal it is kind of a sudden problem, I tried the cd's that failed to finish in my computer later, and only like the first 1 or two tracks are on it. The other disks I used to burn on my iMac before that worked fine, were sony's too so I don't think that this a brand cd-r brand thing. Is this something that is common to iMacs, a defect experienced by others? I don't want to have to waste a bunch of cd's everytime I want to burn a new one. I am curious to know.
That was long winded, but I would really appreciate any advice. Should I just call the apple people, will they tell me to send it them? I really don't want to have to send my computer out (I have a lot of term papers for university coming up). Also is the extended warrantee advisable?
iMac G5 (iSight)   Mac OS X (10.4.4)  

Answer 1

I would just like to thank you for posting all your troubleshooting efforts. This will greatly help the knowledgeable users here in helping you in their attemps to try to solve your problem(s).
In the meantime, have you checked out Mac 101 Lesson 1: Computer Crises the "My optical drive is making funny noises" link? It's possible you may need to try another CD brand.
I've had great success using FUJI based on the users recommendations here.
"Should I just call the apple people, will they tell me to send it them?"
When you have a warranty, always utilize it. Especially if it's free. That's what it's for. As for Apple tech support advising you to "send your computer in" it depends on the problem. Most problems are settled over the phone.
"Also is the extended warrantee advisable?"
For piece of mind, yes. It is totally up to you.
You have up to one year from the date of purchase to make up your mind.