To disable Windows Aero Glass UI follow these steps
Right-click on any blank spot on desktop area and On the pop up right click contextual menu, and select “Personalize”.
Select “Windows Color and Appearance” option.
Disable Transparency, simply uncheck the “Enable Transparency” option.
To disable the Windows Aero theme click on the “Open classic apperance properties for more color options” link located at the bottom of Window Color and Apperance window.
In the Appearance Setting dialog box, select Windows Classic listed in the “Color Scheme” except Windows Aero and click ok
If you want to enable aero glass UI reverse these changes and select windows aero option in the last step.
Using Registry Key
Go to Start—>Run type regedit click ok
Expand and navigate to the following registry key
On the right pane, locate ColorizationColor with type as DWORD. Right click on ColorizationColor, and select Delete on the right click menu. Click on OK to confirm the deletion.
Then right click on registry value titled Composition (type DWORD) and select Modify. Change the value to 0 (by default is 1).
Restart the computer.