SHARP MOBILON HC4600 TOUCH SCREEN GOES CRAZY

Good evening to all.
I have upgraded the RAM on my Mobilon HC-4600 by passing it from 16 to 32Mb
and since the touch-screen doesn't work well.
First at startup, only 3 inches on the left handside of the screen responded
to touches during Recalibration.
It seemed the right hand side of the screen was disconnected.
After recalibration, only the same portion responds but not well, like if
one uses the Shift screen while clicking on a mouse: everything selects
while you move the stylus around.
I loaded the patch for memory and stylus sensitivity but nothing much
better, except the recalibration is possible again, but when confirming the
settings the screen still responds crazy.
I also tried to reput the original 16Mb RAM but I have the same problem.
What can I do?
Why does the screen work well only during recalibration?
What settings could I change in regedit or by loading software.
Thanking you in advance
Louis