Good question. It depends a lot on exactly how you created that disc in the first place. That’s information that you didn’t give me and a lot of the times it’s as simple as not having used the right program, or having chosen the right format in the beginning when the disc was created.
Unfortunately, I don’t necessarily know of a good way to recover from that.
Windows 7 reads Windows XP discs
In general, Windows 7 should be able to read any disc that Windows XP has created.
Put another way, if the disc worked originally and you could see the files in Windows XP after you created it, then I really don’t know of a format-related reason that Windows 7 wouldn’t be able to see those exact same files.
Discs can wear out
One thing that comes to mind is that CD and DVD discs do wear out – or rather, they degrade over time.
Now, normally, a degraded disc will more commonly show a different type of error. Specifically there will usually be CRC or other similar hardware related errors when you try to read the disc. CRC errors are the errors that usually show up when the disc starts to degrade over time. I know that’s not the error you’re reporting, but even so, it’s small a possibility here.
You haven’t told me how long ago these discs were created and of course, what kind of media you used when you created them. If you used inexpensive media, or to put it even more bluntly, if you used cheap media, and perhaps are more than, say, 5 years old, that they’re actually starting to degrade.
One thing to try is to try to read the disc in another machine. Particularly when discs just begin to show signs of degradation the slightly different alignment of different drives in other machines can often allow the disc to be read.
In fact, taking the disc to another machine is just a good idea in general.
The fact is that hardware can fail over time – anything dirt and dust in the mechanism to actual component failure could all lead up to the symptoms that you’re seeing. Taking the disc to another machine can help gather some clues – if it reads readily on the other machine, then perhaps it’s time to see if your disc reader is operating properly.
One last thing I would have you do is to change the Windows Explorer settings to “see everything”, though admittedly this is also a bit of a long shot.
In Windows Explorer go to the View menu, Folder options, and then in the View tab, there’s a long list of options.
I’ve got a couple of articles on changing Windows Explorer settings that will actually show you where these settings are – but the bottom line is in there, select the option to “Show hidden files, folders and drives”.
It’s possible that for some reason the files on this CD have somehow been marked as “hidden”. That actually would result in what you’re describing: what looks like an empty disc, because it’s not showing those hidden files, and yet the disc would still show as using space and having space available.