Are you saying that Apple has replaced your iMac twice? It would be rather unusual to have three Macs with the very same hardware problem in a row, so I'd guess it's software and/or user error related.
No, you cannot install Leopard if your iMac came with Snow Leopard installed (you cannot install any OS version older than what the Mac came with).
There have been widespread reports of Toast not being completely compatible with Snow Leopard - Apple released it much sooner than anticipated and the third party software makers hurried to issue updates to theirs, so there may still be some tweaking necessary.
You also have to remember that the Superdrives in iMacs are the same burners used in laptops - there aren't very many models available that will fit into such a tight space and they've been known to be finicky at best. Add to that the vertical CD insertion/placement - what do you expect? A good brand external burner will always be more reliable and less finicky.
And, it's been suggested for years that it is far better generally to burn at a slower speed to eliminate possible burn errors (and "coasters"). I have no problem with either my internal or external burner, but I would rather wait an extra 2 - 5 minutes and burn at a slower speed. I usually use my external burner and I've never had a coaster. I only use top brands such as Verbatim; i.e. my internal does not like Memorex or Sony.
Did you repair permissions before/after your OS install or update or the Toast install/update? Have you tried to uninstall Toast, repair permissions, restart, and reinstall Toast?
Again, I seriously doubt that 3 different machines have the exact same hardware problem...
So, what media (brand) have you been using?
What about my question re. repairing permissions?
Have you uninstalled Toast incl. the .plist file and reinstalled it?
Have you tried burning with something other than Toast (such as Disk Utility, iTunes, etc)?
It is difficult to help until you do some troubleshooting, post the results, and give us more detailed information. Just saying that it doesn't work is not at all helpful.
Your right, maybe it's not a hardware problem, but it's the same problem with the ext dvd burner connected to the iMac. But when connected to my Late '08 Macbook running OSX 10.5.8 I have no problems.
So it leads me to believe it's a software or OS problem.
I use Sony and Memorex DVDs.
I repair permissions weekly and did clean installs with toast 10.4. (deleted old .plists files, etc)
I have tried to burn discs with iTunes, Disk Utility and Burn with no success.
I have been doing troubleshooting since day 1 of getting my new iMac.
I have 2 other Macs in the house running OSX 10.5.8 with no burning problems with the same software.
Why is it hard to believe 3 machines have the same problem???
Why don't you buy a small package of Verbatim discs and try burning with them. Some burners are more finicky than others, but you are using precisely the two brands which mine does not like and they have a bad track record here on these boards (especially Memorex). I would not buy a spindle pack until after I've ascertained that the brand/type will work; also, any brand can have a bad batch.
I just ran across this problem with my new 21.5" iMac running 10.6.2 as well. Strange thing is, it will successfully burn CDs if I set the speed to 2x with no buffer underrun protection. Stranger still, it burns at an average speed of 9x.
I'm using Verbatim white hub-printables, P/N 94755 and Toast 8.
Turns out it was Toast not playing nice with 10.6.2. After several more burns, I wound up a couple coasters, so I tried burning with Peak 6.1 -- no problems at any speed. Guess I'm in no hurry to upgrade Toast!
Well, if you have any Supwerdrive problems.... it's a Firmware problem.
Hard to contact Roxio... i sent this link to the forum... No Response.
If i use another DVD Burner (Sony) no problems. So it's in the Internal Superdrive.
Call Chris 1-877-388-0879 ext. 86303 he's the expert at Apple for DVD Problems.
i guess the more ppl Call, the faster the problem will be solved.
(Peak 6.1 - Thats not a comparable program to Toast? Is'nt that a sound editor program?)
I need to Copy DVD once and a while, Never any problems with Toast.
Now it does does not work properly on any speed. 2x 4x 8x... No Way.
Totally unstable with Toast. Stacks of Coasters. It's a Firmware problem.
And i want it to be solved. (Now on the look out for Screen Flickering.....too) My 12 year old other iMac never had a problem....
I'm burning holiday music mix CDs for stocking stuffers, and when the tracks I'm working with don't require anything more than a little normalization, I use Toast most of the time for audio CDs. Since Toast was producing an occasional coaster, I went with Peak. It's complete overkill for this particular use, but it's been rock-solid on this new iMac.
I too have a 3-week-old iMac which frequently gives 'interface error 5 the connection is not stable' when trying to burn DVD's in Toast 10, resulting in an abundance of 'coaster' discs. I do not believe that this is a Toast problem as I also get 'verification failure' about 50% of the time when burning through Finder. I have talked to Roxio who do not accept that Toast 10 is at fault; they suggest that a firmware update may be necessary for the optical drive (GA11N). I have also talked to Apple and their suggestion is that there may be a problem with the GA11N drive which needs to be checked by an Apple Tech. I have no problems burning DVD's using Toast 10 on my MacBook (5.1)
I also have the same problem with a brand new 21" iMac 2009 model with OSX & Toast 10.04
Snow Leopard
Version 10.6.2
Build 10C540
Processor: 3.06GHz Intel Core 2 Duo
Memory: 8 GB 1067 MHz DDR4
HD: 500gig
The error is:
Interface Error: 5
The connection is not stable.
I have tried four different brand names of discs and disconnected everything and do not load any programs at login; I even disconnected from the network.
I am really disappointed that I spend all this money to do something as basic as burning a disc and it does not work.
I'm having the same problem. But with an older version of Toast.
I'm using Snow Leopard (10.6.2) with burner:
HL-DT-ST DVDRW GHA11N According to System Profiler, it is capable of burning at 2x, 4x and 8x speed.
I've been able to burn using iDVD and also using Disk Utility. So, the problem doesn't seem to be with the hardware.
I've only created 2 coasters so far (TDK 16x DVD-R). But considering that the last time I made a coaster was about a year ago, this doesn't make me a happy camper...
The worst part is that the disc gets stuck in the burner and you have to jump through several hoops to get it to eject.
very frustrating.
I've owned several macs in the past and have never had a problem like this before!
