The steps in this document have been found helpful in solving many problems associated with Windows 7 Update Error Code 643 set icon unsuccessfully problems, so, you can have a try.
1.First of all click the Start button to view the Start Menu. Then choose the Control Panel option.
2.After click Control Panel, enter into System and Security, then click into Windows Update.
3. Now you are at the Windows Update section of our Window 7 Control panel. You can manually look up for any new updates by clicking the Check for updates button
One way to update Windows 7 - To turn on automatic updates in Windows 7:
1.Select the Start button
2.In the search box, enter Update, and then, in the list of results, select Windows Update.
3.In the left pane, select Change settings, and then under Important updates, select Install updates automatically (recommended).
4.Under Recommended updates, select the Give me recommended updates the same way I receive important updates check box, and then select OK.
5.Reboot your computer after you have done all these steps.
6.Voila! Windows will install updates automatically by itself and there is no need to keep an eye on it any more.