h5450 has a single white line across the screen.

Okay, here's a challenge for the hardware gurus out there (I think!)
 
My 5450 has mysteriously gained a single pixel width horizontal white
line across the display (about 3.5cm down from the top).
It appeared after working normally in my USB cradle, synced to my PC. I
removed the ipaq to
go home one evening, and when I turned it on again, I got a blank
screen, so I reset and there was the line.
>From then on, I also found I had to reset the ipaq each time I turned it
back on to get it to boot at all, otherwise I
just got a blank screen (mostly). (Sometimes there where vague faded and
changeable shapes discernible).
 
After a reset, the unit behaves normally, except for the white line
across the screen, which doesn't go away no matter what I do.
 
I have been thru the whole ROM re-flash exercise. No change. I have even
loaded Bootldr and Linux on the device to prove its not my WinCE image,
but still the line remains.I did the reflashes to try and eliminate the
possibility that I had a corrupted ROM, or Boot partition.
 
Have reluctantly concluded that therefore I have a hardware failure. My
question is, which component is likely to be at fault?
eg is it a new screen I need (why would it fail on just one pixel
line?)? Or is it the main board, LCD controller (or maybe display
memory)?
Any other suggestions welcome, or pointers to further information that
will help me in my quest to localise the fault.
 
Given that I currently have Bootldr running, and can issue low level
instructions to examine registers/memory,
is there a series of tests I could do to check where the problem likely
lies before I go ordering the wrong replacement part?
 
I don't really want to go to the extent of getting into it via JTAG, but
will if need be (would that help anyway?), if anyone can point me in the
right direction, please?
 
Any thoughts/suggestions on how I can fix this? At a pinch, I could live
with the permanent line,
but I am really getting sick of having to reboot each time I turn on.
 
TIA
 
Garry
 
 

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