The logon screen may be clipped on a Windows Vista-based computer after you reset the screen font size to the “Larger scale (120 DPI)” setting, and then you restart the computer
On a Windows Vista-based computer that has a 1280 by 800 screen resolution, you reset the screen font size to the Larger scale (120 DPI) setting. However, when you restart the computer, you see that the logon screen is now clipped. Therefore, you have to scroll down the logon screen to enter your password.
Note: This issue does not occur when you use the Default scale (96 DPI) setting.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB953826.