No puedo instalar IE8

cuando intento instalar ie8, este,termina sin istalarse y me pide que
reinicie el equipo rpara desacer los cambios.
abro ie8.log y en el se lee lo siguiente:

[ie8.log]
0.422:
=> 0.422: 2009/01/21 13:54:43.515 (local)
0.422: c:\adaeb2cba56d658fde569b896673\update\update.exe (version 6.3.15.0)
0.610: Hotfix started with following command line: /quiet /norestart /er
/log:C:\WINDOWS
0.657: In Function GetReleaseSet, line 1240, RegQueryValueEx failed with
error 0x2
0.719: IECUSTOM: Scanning for proper registry permissions...
1.563: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.563: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid
1.563: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.563: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid32
1.563: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.578: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.578: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.578: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.578: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
2.297: IECUSTOM: Scanning for proper registry permissions...
2.688: IECUSTOM: Scanning for proper registry permissions...
3.110: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
3.297: IECUSTOM: Backing up registry permissions...
3.297: IECUSTOM: Finished backing up registry permissions...
3.297: IECUSTOM: Setting new registry permissions...
3.297: IECUSTOM: Unable to clear DACLs
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
3.297: IECUSTOM: Finished setting new registry permissions...
3.297: IECUSTOM: An error occured verifying registry permissions. ERROR:
0x80070534
3.297: DoInstallation: CustomizeCall Failed: 0x3f5
3.313: IECUSTOM: Restoring registry permissions...
3.328: IECUSTOM: Finished restoring registry permissions...
3.328: No se puede escribir la clave del Registro de configuraciones.
3.328: La instalación de Internet Explorer 8 no ha finalizado.
3.328: Update.exe extended error code = 0x3f5
0.578:
=> 0.578: 2009/01/21 19:21:46.703 (local)
0.578: c:\719b4ae60096a59712c3\update\update.exe (version 6.3.15.0)
0.625: Hotfix started with following command line: /quiet /norestart /er
/log:C:\WINDOWS
0.656: In Function GetReleaseSet, line 1240, RegQueryValueEx failed with
error 0x2
0.688: IECUSTOM: Scanning for proper registry permissions...
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\ProxyStubClsid32
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}\TypeLib
1.703: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
2.344: IECUSTOM: Scanning for proper registry permissions...
2.688: IECUSTOM: Scanning for proper registry permissions...
3.219: IECUSTOM: Unwriteable key
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
3.438: IECUSTOM: Backing up registry permissions...
3.438: IECUSTOM: Finished backing up registry permissions...
3.438: IECUSTOM: Setting new registry permissions...
3.453: IECUSTOM: Unable to clear DACLs
HKCR\Interface\{34A715A0-6587-11D0-924A-0020AFC7AC4D}
3.453: IECUSTOM: Finished setting new registry permissions...
3.453: IECUSTOM: An error occured verifying registry permissions. ERROR:
0x80070534
3.453: DoInstallation: CustomizeCall Failed: 0x3f5
3.469: IECUSTOM: Restoring registry permissions...
3.500: IECUSTOM: Finished restoring registry permissions...
3.500: No se puede escribir la clave del Registro de configuraciones.
3.500: La instalación de Internet Explorer 8 no ha finalizado.
3.500: Update.exe extended error code = 0x3f5

¿Que estoy haciendo mal?.

Una ayuda sera bien recibida