Sounds like there's a hardware problem with the display, and your problem is just going to escalate. If it's still under warranty, now would be a good time to make good on that agreement. Otherwise, start speccing out a new PDA.
I have vertical lines appearing on one side of my sony clie nx60 screen. They were 2 and have now increased to 4. I am scared the whole screen will some be taken over. Can someone tell me the cause of this and how it can be stopped.