A field report! - NAVI CD not Lebar, read errors CD-defect

Has anyone ever had also the problem that the Navi Navi CD no longer wanted to read,
went into operation only after half an hour, "Please insert a suitable CD, the CD is unreadable"
"CD defective" etc.?

I drive since 2006 Octavia with the Navi "Nexus". Now so - gradually - precisely this mistake with me occurred.
Only sporadically, then every time I start the car in the morning.
Before I begin a so any crap, I've read through various forums. The VW and Audi forums there were very helpful,
because this problem seems to occur more frequently in VW and Audi. At least in these forums is much more about it.
Good. - Most opinions were in the direction of "leave absolutely clean by a specialist workshop" and "in no case
use a cleaning CD "and" there is a NAVI Doc ".
A few comments were made but also of "reckless" who attempts a cleaning CD, and apparently with success.

That there is ever such a cleaning CD's so far eluded my knowledge.
So I thought, "the NAVI is now five years old, if you bring it to the Navi-Doc, can be expensive which might, as with installation and removal.
So I have myself decided also to belong to this "reckless" and tried it with a cleaning CD.
If it does not work, kannste still to NAVI Doc. Or possibly. The same buy a more modern device,
perhaps the same with new car around it.

Preparations:
So I bought the most expensive cleaning CD was to get. (Approximately 11 Euros / incl. Shipping) course with online Review.
Only upon receipt of the CD, I read on the packaging that the CD is "NOT FOR CAR / NAVI suitable".
This words were not in the item description of the well-stocked online stores even in the aforementioned report.
Now I have not let me confuse.
Furthermore, I have found me "Air Spray". But not for computers and electrical. Equipment !!!
There are special compressed air in a can for photo-optics and sensors.
The difference lies in the ingredients of the compressed air.
Oh yes - and dab a few towels for welding.

Procedure:
First I NAVI CD away. Then a bit put the tube of Dusters in the slot and blown out the drive vigorously.
(With multiple short bursts of air from different locations of the slot.)
I then inserted the cleaning CD and run several times.
On my being a piece of music of approximately 30sec length, which starts from himself all over again.
After a few runs, I have the cleaning disc is removed and once again blown out the drive vigorously with compressed air, so that the dirt, the CD has possibly solved., Also does not remain in the drive.
When handling the Compressed-Air Spray's I have kept strictly to the instructions on the can,
ie can no longer tend to be 30 degrees, no fast movements during spraying, etc.

Conclusion:
What can I say. Is now a few days ago and my navigator runs since then accidents.
Whether that now want to imitate someone or not, each is left to itself and is at your own risk.
Here I can express no advice.
Maybe, too, that I have been lucky and has not done the cleaning CD broken, as described in some forums.

The product description on Amazon reads like a promotional text.
Only once you have received the goods, you can read on the packaging,
that these cleaning CD is "not for auto / Navigation" suitable.
For these missing IMPORTANT NOTE 2 stars less.