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. I know that’s not the error you’re reporting, but even so, it’s small a possibility here. 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. Now, normally, a degraded disc will more commonly show a different type of error. One thing that comes to mind is that CD and DVD discs do wear out – or rather, they degrade over time. 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. In general, Windows 7 should be able to read any disc that Windows XP has created. Unfortunately, I don’t necessarily know of a good way to recover from that. 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. It depends a lot on exactly how you created that disc in the first place.