This problem is discussed in many threads.
My advice, try opening your computer with a clean DOS disk, floppy or 256mb flash drives. (1gb drives are not recognized by bioses so as to boot)
Than, get an OAKCDROM.SYS file, an MSCDEX.EXE file.
Edit a Config.sys file. Write the line:
Than, after your comp. boots, look at the lines where your drive is recognized.
Than write the line:
MSCDEX /d:12345678 /l:f
that 12345678 is the name given to your drive by OAKCDROM.SYS. May be different.
You can get that label at the boot, where your drive is recognized.
Than, try your DVD-R's. I bet you'll see all of them cleanly.
But won't be able to copy, because DOS can't see 2+ GB HDD Drives...
If you can see your disk that way, carry the subject to my post.
Because it is about Windows not recognizing DVD-R's. Not the computer or drive....