White Blank Screen....Help !!

i,
I get this strange problem on my 8703e handset. The screen goes plain white (no hourgalss)....while other phone fucnctions work normally (i.e. i can pick calls by pressing green button, or hear messages delivering, can see LED notificationsI but I dont see anything on the display becouse it is simple white screen....
After few hours this problem automaticall goes....and then return back suddenly after some days (I dont know why)
One more Important thing - before this screen goes blank, the keypads become non responsive, phone just don't respond so to make it responsive I have to do a battery pull (to hard restart) and then it starts but only with a blank white screen.

Does anybody have any idea about this problem or its solution ? Has anybody encountered this problem before ?

Any Help/suggestion will be highly appreciated.

Regards,
-jai