Windows 7 system prompts you to perform a clean boot to resolve this issue

"Clean boot" is similar to http://www.aliyun.com/zixun/aggregation/34134.html > Safe mode, when you start your computer in this mode, you will run only the minimum number of startup programs and services. For example, if there is no error when you start your computer in Safe mode, a startup program or service may be causing the problem. When you troubleshoot a problem with a clean boot, you can try to turn off all startup programs and services when you start your computer, and then turn the startup items on or off systematically until you can pinpoint the startup item that caused the error.
Step 1: Perform a clean boot
Note: If your computer is connected to a network, network policy settings may prevent you from performing these steps. We strongly recommend that you do not use the System Configuration Utility to modify advanced startup options on your computer unless instructed to do so by a Microsoft technical support engineer. This operation may make your computer unusable.
A. Log on to the computer with an account that has administrator privileges.
B. Click the Start button, type Msconfig.exe in the Start search box, and then press Enter to start the System Configuration Utility.

C. On the General tab, click Selective Startup, and then click to clear the Load Startup items check box. (The Use original Boot.ini check box is not available.) ）

D. On the Services tab, click to select the Hide All Microsoft services check box, and then click Disable All.

Note: Following this procedure will keep Microsoft services running. These services include networking, Plug and Play, event logging, error reporting, and other services. If these services are disabled, all restore points may be permanently deleted. Do not perform this operation if you need to use the System Restore utility with an existing restore point.
E. Click OK, and then click Restart.
Step 2: Enable half service
A. Start the System Configuration Utility by following steps 1a and 1b.
B. Click the Services tab, and then click to select the Hide All Microsoft services check box.
C. Click to select half of the check boxes in the Services list.
D. Click OK, and then click Restart.
Step 3: Determine if the problem occurs again
If this problem persists, repeat steps 1 and 2. In step 2, click to clear the Half check box that was previously selected in the Services list.
If this problem no longer occurs, repeat steps 1 and 2. In step 2, select only the remaining half of the check boxes that are not selected in the Services list. Repeat these steps until all the check boxes are selected.
If only one service is selected in the Services list, and the problem still occurs, the selected service is the service that is causing the problem. Please go to step 6. If no service is causing the problem, go to step 4.

Step 4: Enable half the start item
A. Perform a clean boot by repeating step 1.
B. Click the Startup tab, and then click to select half of the check boxes in the Startup items list.
C. Click OK, and then click Restart.
Step 5: Determine if the problem appears again
If this problem still occurs, repeat steps 1 and 4. In step 4, click to clear the Half check box that was previously selected in the Startup items list.
If this problem no longer occurs, repeat steps 1 and 4. In step 4, select only the remaining half of the check boxes that are not selected in the Startup items list. Repeat these steps until all the check boxes are selected.
If only one startup item is selected in the Startup Items list, and the problem persists, the startup item that is selected in the list is the service that is causing the problem. Please go to step 6.
If there are no startup items that cause this problem, it is most likely caused by Microsoft services. To determine which Microsoft service may be causing the problem, repeat steps 1 and 2, but do not select the Hide all Microsoft services check box in two steps.
Step 6: Solve the problem
After you determine the startup item or service that is causing the problem, contact the program manufacturer to determine whether the problem can be resolved. Alternatively, run the System Configuration Utility, and then click to clear the check box for the problem item.
Step 7: Reset the computer to start normally
After troubleshooting is complete, follow these steps to reset the computer to start normally:
A. Click the Start button, type Msconfig.exe in the Start search box, and then press Enter.

B. On the General tab, click the Normal startup option, and then click OK.

C. When you are prompted to restart your computer, click Restart.
How to start the Windows Installer service when the system service is not loaded
If you do not start the Windows Installer service when you run Setup, you may receive the following error message:
Unable to access the Windows Installer service. Contact your support personnel to verify that the Windows Installer service is properly registered.
If you clear the Load System Services check box, you cannot start the Windows Installer service. To use the Windows Installer service without loading the system service, you must start the service manually. To do this, follow these steps:
1. Click the Start button, right-click Computer, and then click Manage.
2. In the console tree, click Services and Applications, and then click Services.

3. In the details pane, right-click Windows Installer, and then click Start.