Application Data has been moved. To see where it has been moved to, open a
command prompt and type "dir /a". It will identify Application Data as a
junction and will show you the new location in brackets.
Many folders used by earlier versions of Windows have been moved to a new
location or given a new name in Windows Vista. However, the old folders can
still be seen if you have enabled Show Hidden Files.
Notice they are displayed with a transparent icon and a shortcut symbol.
Although these look like folders, they are actually what is known as a
junction. Junctions behave like shortcuts, but look just like regular folders.
Their purpose is to silently redirect programs that access them to their
Windows Vista equivalent.
Since junctions aren't really folders, it is not possible to access them,
and any attempt to do so will give you an "Access Denied" error.