What is "C:$Extend$Reparse:$R:$INDEX_ALLOCATION" in Win7?

ProcMon.exe tells me that many different processes including ones owned by standard users, admins, and the SYSTEM user are receiving "ACCESS DENIED" error results when trying to read "C:/$Extend/$Reparse:$R:$INDEX_ALLOCATION".

Google retus nothing useful from MSDN, but i assume these are NTFS or Windows Search folders. What processes need to be able to r C:$Extend? w? x?