Instalaltion IE7 impossible

Bonjour,

Je tente de faire la mise a jour vers IE7 sur un poste en xp pro-sp3, je suis pourtant sur le compte administrateur, l'installation se termine mal et on m'indique que l'installation d'IE7 n'a pas été faite...

voici le contenu du fichier c:\windows\ie7.log

0.438: 2008/12/08 11:42:05.375 (local)
0.438: c:\69d1324cccee58bf14b8\update\update.exe (version 6.2.29.0)
0.469: Failed To Enable SE_SHUTDOWN_PRIVILEGE
0.469: Hotfix started with following command line: /quiet /norestart /er /log:C:\WINDOWS 
0.469: IECUSTOM: Scanning for proper registry permissions...
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid32
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.500: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
2.735: IECUSTOM: Scanning for proper registry permissions...
3.094: IECUSTOM: Scanning for proper registry permissions...
3.563: IECUSTOM: Unwriteable key HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
3.766: IECUSTOM: Backing up registry permissions...
3.782: IECUSTOM: Finished backing up registry permissions...
3.782: IECUSTOM: Setting new registry permissions...
4.000: IECUSTOM: Unable to clear DACLs HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
4.000: IECUSTOM: Finished setting new registry permissions...
4.000: IECUSTOM: An error occured verifying registry permissions. ERROR: 0x80070534
4.000: DoInstallation: CustomizeCall Failed: 0x3f5 
4.000: IECUSTOM: Restoring registry permissions...
4.047: IECUSTOM: Finished restoring registry permissions...
4.078: Impossible d'écrire la clé du Registre de configuration.
4.125: L'installation du Internet Explorer 7 ne s'est pas terminée.
4.125: Update.exe extended error code = 0x3f5

Que se passe t-il??

merci