DVD won't mount on desktop

[the posse]

I have done quite a few backups of DVDs and they all work fine when i use them but then gradually some of them stop working and i keep them all in a clean case and i use verbatim DVD-rs
I.E blocks and freeze frames but the problem is now when i try and mount any DVD on my imac it won't mount.
I use mactheripper to decrypt and DVD2ONEX to compress and toast 6 to burn.
Am i not doing something right here.
All my friends DVD backups are fine but they all use windows and DVDshrink.
Any help would be greatly greatly appreciated.
Thanks Scott

[Case]

Is the lens of the writer clean (e.g. dusty environment)?
What drive is in the iMac (e.g. Sony, Matshita, Pioneer, model nr.)?
What age is the drive?
At what speed did you burn?
For what speed are your discs certified?
Did you use Verbatim "DataLife" or "DataLifePlus", the latter being their premium dye.

[the posse]

I've had my mac for a year and a half and i do live in quite a dusty enviroment.the drive is a pioner 105 DVD-R and the discs i use are datalife plus 8x certified.I always burn at the BEST setting in toast.
I hope this info helps you to help me.
cheers mate
Scott

[terryj]

Going back and looking at the DVD Media forum on the left
of screen ( hint, hint), you can tell that some users
have reported problems AFTER BURN with these discs,
as blemishes show up making the discs unplayable.

https://www.videohelp.com/dvdmedia.php?selectmedia=1293#comments

The disks I have are not very good, I have not ran K-probe or anything. Looking at the back of the disk it looks perfect before anything is writen to it, but after burning the disk you can see small blemishes in the dye, and the video skips and pauses when played, I believe it is do to these blemishes. My media code is slightly diferent than what is reported here, but it is the closest I could find.
full media code reported by DVDInfoPro is:
Complete Media Code
00000000 08 02 00 00 A1 0F 02 00 00 03 00 00 00 25 E1 BF .............%..
00000010 00 00 00 00 00 00 03 4D 43 43 00 00 00 00 00 30 .......MCC.....0
00000020 30 33 00 38 23 54 37 12 02 42 6E 02 A8 6B 15 15 03.8#T7..Bn..k..
00000030 0B 0B 08 08 01 19 1B 0C 0C 0C 0D 01 00 00 00 00 ................

Blocks and Freeze Frames, as you report, are indicitive of
BAD MEDIA, period. All discs ( with exception of Taiyo
Yuden thus far) suffer from defects in the run at some point.

I usually chalk it up to " FRED" was sleeping on the job
when he should have been doing quality control.


My reccomendation; check the DVD Media forum
( again, hint, hint)
BEFORE buying media to make sure that what's out in the
market isn't crap. If a disc brand has more than three
negative reports within a 60 day period,
from the time I'm looking to purchase, chances are
theres bad media at there, quality control issues, etc.
I skip it and find another with good reports.

[thoughton]

I don't think this a media error. How long does it take for them to stop working? Verbatims should not have any problems, so you must be doing something else.

As well as all the things Case said, is there any chance you're exposing these discs to the sun? What pens are you writing on them with? Oil based or alcohol based?