Recommended method to clean DVD disks

[Gringo6]

My old Vista computer "bit the dust" so now that I have a new one I'm trying to get it all reloaded.
Most is going well except for FSX. It will work fine until about 2/3 of the way thru disk 2 when
it all stops because it cannot find some file. The name of the file escapes me right now but its
always the same file on each of the various tries.

1. There is no visible mark on the surface of the disk.
2. I purchased FSX new when it first came out and the disk has only been used 4 or 5 times since.
3. Maybe there is some problem that I cannot see so what is the recommended method to clean
a DVD disk ?
4. If that fails I'd like to know if M/S still supports FSX ?

I'm reluctant to purchase a used copy of FSX on the net because it might have the same problem.
I would have sworn that my copy was pristine but it seems not.

Any advice will be appreciated.

[OldAirmail]

If there are no marks on the disk then it's probably a bad factory burn.

This may not be a problem at all.

That bad file has a good chance of being, relatively, unimportant like a missing village Siberia.

Try re-installing it. When it gets to the problem(s) just click on Retry. If it still doesn't work after a couple of times then just click on Ignore.

I'm betting that you'll never know, or need, that file.