visual studio ultimate 2012无法安装

安装net 4.5时

日志最后几行

[04AC:16A0][2012-08-24T21:13:22]: Detected package: vs_postclean_vs, state: Absent, cached: None
[04AC:16A0][2012-08-24T21:13:22]: Detected package: ultimate_finalizer, state: Absent, cached: None
[04AC:16A0][2012-08-24T21:13:22]: Condition 'NOT (CurrentOperation = "Uninstall")' evaluates to true.
[04AC:16A0][2012-08-24T21:13:22]: Condition 'NOT (CurrentOperation = "Uninstall")' evaluates to true.
[04AC:16A0][2012-08-24T21:13:22]: Condition 'NOT (CurrentOperation = "Uninstall")' evaluates to true.
[04AC:16A0][2012-08-24T21:13:22]: Condition 'CompatibilityMode = 0' evaluates to false.
[04AC:16A0][2012-08-24T21:13:22]: Condition '(VersionNT < v6.1)' evaluates to false.
[04AC:16A0][2012-08-24T21:13:22]: Condition '( VS11BETA_MSENV_DLL_EXISTS ) AND ( VS11BETA_MSENV_DLL_VERSION < v11.0.50324.0 ) AND (CurrentOperation = "Install")' evaluates to false.
[04AC:16A0][2012-08-24T21:13:22]: Condition '(NOT IsLanguagePack) AND ( CurrentOperation = "Install" ) AND ( FLP_Version > v11.0.50727 )' evaluates to false.
[04AC:16A0][2012-08-24T21:13:22]: Condition '(VersionNT = v6.2) AND (netfxfullredist_43_DetectKey < v4.5.50709)' evaluates to true.
[04AC:16A0][2012-08-24T21:13:22]: MUX: Stop Block: NetFXVersionBlock : 此计算机上安装的 .Net Framework 未达到最低版本要求: 4.5.50709。
[04AC:16A0][2012-08-24T21:13:22]: MUX: Detect Completed
[04AC:16A0][2012-08-24T21:13:22]: MUX: Wait for View to be loaded
[04AC:0C88][2012-08-24T21:13:22]: MUX: Detect Completed, now create view
[04AC:0C88][2012-08-24T21:13:23]: MUX: User feedback control is Enable because opt-in value is NotDefined
[04AC:16A0][2012-08-24T21:13:23]: MUX: View loaded
[04AC:16A0][2012-08-24T21:13:23]: MUX: Go to Blocker page.
[04AC:16A0][2012-08-24T21:13:23]: Detect complete, result: 0x0
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