Hi,
Unfortunately you cannot disable taskbar transparency in Windows 8. The only option to avoid transparency is to change the color intensity in Personalize.
- Right click on the desktop
- Select Personalize
- Select Color
- Use the Color intensity slider to adjust the intensity. You may also use the Color Mixer (just under the slider) to adjust the brightness.
- Select Save changes
Hope it helps. Get back to us for any issues related to Windows. We will be happy to help you.