Panasonic TC-L42D2 Technical Manual page 87

Conclusion: Exchange the A board
Source Driver
LCD Panel (Gate Driver is in Panel)
Diagnosis
OSD (On Screen Display) is generated at IC8001 Nile-TCON in A board.
So, exchange the A board.
Picture Defect (7) (D Series)
Gate
Driver
LVDS DATA
Control DATA
TC board
LVDS DATA
A board
(LVDS= Low Voltage Differential Signaling)
Sample Picture
Abnormal OSD
Slide # 87