In an office the accountant made a monthly report using Excel on an PC with Windows XP
It is password protected and a read only file One of "his supervisor tried to backup it to CD R disk using the CD writing program of XP. He got the error message that said ?It is read only file"

This is VERY PROPER for a file on CDR. Since a CDR is read-only, the message is as expected.

"?If he use Nero or other program he can write this report to CD R Then when he brought this CDR to his PC with Windows XP and used the CD writing program of XP to write some new files to the CDR .He got the same error message
He had to use Nero to write other files (not read only) to this CDR
Do you have any idea?"

Believe it or not, again this seems proper. XP's native CDR support is very entry level and may fail for many reasons.

Since you have the file on CDR and can copy it out to the hard disk, then remove the Read-only flag on the file that is now on the hard disk, what issue remains?