I had hoped to use System Restore to solve the problem. However, when I go into System Restore, the window appears with a title bar. The rest of the window content is completely white.
A similar thing happens when I go into "User Accounts." The window contains nothing but the title bar, the back and forward buttons and the home button. The rest of the window content is white.
There are a number of other issues on the computer, but I think they are related to the above. I'm thinking a missing or corrupt dll which is used to display window content.