昨天安装2008R2的时候出错了，于是开始卸载，安装，但是由于卸载的不干净，导致mssql2008R2安装失败。总是在“Action "PostMsiTimingConfigAction" failed during execution”的地方执行不下去。于是查询了解决方法，并解决之。

具体解决如下：

Since you removed an existing SQL Server installation before installing SQL Server 2008 R2, the error might be caused by the leftover previous SQL Server installation. I suggest you uninstall the existing SQL Server instance by the following steps:
1. Make sure you have administrative rights on the computer
2. Uninstall the existing SQL Server 2008 and all the components from the control panel. Remember to backup the user databases before uninstalling SQL Server.
3. Backup the registry.
4. Delete the following keys in regedit:
--HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server
--HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer
5.  Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall  and delete all the sub-keys referencing SQL Server.
6.  Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services and delete all the keys referencing SQL Server.
7.  Rename all the SQL Server folders in the computer.
8. Try the steps in the “If you experience problems” section and “Step 3: Uninstall the support components” section from:
http://support.microsoft.com/kb/909967
9. Reboot the machine.
10. Reinstall SQL Server 2008 R2.

---如果安装失败

I find that some components need to be uninstalled. As follow:

Microsoft Sync Framework Runtime v1.0(x64)

Microsoft Sync Services for ADO.NET v2.0(x64)