if you try to overwrite,let s say C:/WINDOWS/RESOURCES/THEMES/LUNA/LUNA.MSSTYLES you ll be unplesently suprised.the most obvious the file size should be 888kb and it s again reverted to 4.09mb.that means something reoverwrited the file.the source of system files backups is dllcache folder.i think it s under C:/WINDOWS/dll_cache/*.* so to stop this from happenin,simply delete all files in this folder.your windows should be 500mb lighter now! plus now you can overwrite luna.msstyles.you ll get a msg blah blah blah on which you should answer ,,cancel,, on another ,,are you sure..,, yes and that s all.under C:/WINDOWS/system32 or whatever works for your win (in run type o/o windir o/o/system32) and locate sfc.exe (system file checker) delete it.you can also delete sfc_files.dll to disable blah blah blah msg but that ain t recommended. also before you do anythin i am not responsible for possible damage to your system. tip: do not keep original windows xp cd while deleting/overwriting files.