Files on CD-RW not showing after initial burn

I am having a problem with my Windows 7 Pro edition when burning data to a CD-RW.

When I add new data to existing data already burned on the CD-RW, the data has been written correctly to the disk, but when I view the disk after writing the new data, I never see the new data...the only data I see is the data that was written to the CD-RW at the FIRST burning. When I place my CD-RW in my other computer with Windows XP, all the data appears...initial burning and all subsequent burnings; place it in my Windows 7 CD drive and NO secondary data is showing.

In one program I have for burning, I actually get a dialog box saying "the data has been written correctly to the disk, but the number of files does not match the expected file count. Most likely, the file system structure has not been written correctly and some files will not appear on the disk." What is going on with this "file system structure has not been written correctly?"

This is a new wrinkle in the sheet for me. I have 5 CD/DVD read/write drives, and they all work the same...only initial files show and other files are not visible when re-burning to a CD-RW. It is really a new Agatha Christie mystery to me.

Any help with this frustrating problem would CERTAINLY be appreciated. Thanks in advance.

To Lemur,
Thanks very much for your suggestion. No, I did not format the CD-RW since I never had to do that in Win XP and it never occurred to me to do that. I don't truly understand why I would have to do that in Win7 when never did in XP, but I am not that techy savvy; I will certainly act on your suggestion; it just might be my problem. Although, I did put the CD into another machine with WIN7 and it showed all the files with no problem at all. Thanks again.