Probably not a folder. Sounds like it could be a windows shortcut file with a jpeg extension, but it doesn't make sense for it to be an actual folder.
I have a DVD full of "jpg" files stored in different folders. This was
created under Windows Vista. I now have an iMac - OS X. All folders from
the DVD open but one. Under OS X, this one folder has "jpg" in the "kind"
line of "Get Info". Obviously this means it won't open in OS X (It will still open under Windows Vista).
Is there a way to change the "kind" value back to "folder" in OS X? I have looked at lots of utilities that change the file type. But none claim to change the "kind" value.