I found an issue : At T-12, IE7 installation, and (with guirunonce) on first login delete many files into dllcache, and after install KB947864. That operations are unattended. This is my AutoIt script to delete the old files into dllcache (easy) : #NoTrayIcon Opt("RunErrorsFatal", 0) $d = @WindowsDir & "\system32\dllcache\" FileDelete($d & "advpack.dll") FileDelete($d & "dxtmsft.dll") FileDelete($d & "dxtrans.dll") FileDelete($d & "extmgr.dll") FileDelete($d & "icardie.dll") FileDelete($d & "ie4uinit.exe") FileDelete($d & "ieakeng.dll") FileDelete($d & "ieaksie.dll") FileDelete($d & "ieakui.dll") FileDelete($d & "ieapfltr.dat") FileDelete($d & "ieapfltr.dll") FileDelete($d & "iedkcs32.dll") FileDelete($d & "ieframe.dll") FileDelete($d & "ieframe.dll.mui") FileDelete($d & "iernonce.dll") FileDelete($d & "iertutil.dll") FileDelete($d & "ieudinit.exe") FileDelete($d & "iexplore.exe") FileDelete($d & "inetcpl.cpl") FileDelete($d & "jsproxy.dll") FileDelete($d & "msfeeds.dll") FileDelete($d & "msfeedsbs.dll") FileDelete($d & "mshtml.dll") FileDelete($d & "mshtmled.dll") FileDelete($d & "msrating.dll") FileDelete($d & "mstime.dll") FileDelete($d & "occache.dll") FileDelete($d & "pngfilt.dll") FileDelete($d & "url.dll") FileDelete($d & "urlmon.dll") FileDelete($d & "webcheck.dll") FileDelete($d & "wininet.dll") Edit : Also possible with batch... (del /Q file.dll)