First, try to change the subject of the computer. Win7 system, the right mouse click on the desktop space, select "Personalized", in which you can change the theme and adjust the desktop color matching. As shown in the figure:
Method Two, Win7 system right-click Computer to select the Properties button, then click on the "Advanced system Settings", open the System Properties window, now switch to the "Advanced" option, click the Performance "Settings" button below, select "Adjust to the recent appearance" on the visual effect. As shown in the figure:
Method Three, if the Win XP system, first click on "Start-Control Panel", open Control Panel-management tools-services to see if the "Themes" service has been started. Then right click on My Computer, select "Properties", select "Advanced", and view the "Use visual styles on Windows and buttons" tab has been selected; Finally go to the Display Properties dialog (right side of the table--properties)--appearance--Windows and buttons--windows XP style. You can change the style for it.
Method IV, if the above method does not work, it is estimated that the system has failed. Try to repair the system, you can restart the computer boot hold F8 key to enter the advanced options, and then select "Last Known Good Configuration" into the system repair, in safe mode to see if the taskbar is also white phenomenon, no words will be restarted to enter the normal mode. Of course, about system repair can also be repaired with the system's own restore function and system disk.
Finally, if it doesn't work, then reload the computer system.