Hp Prime screen has interference's lines when touched with finger

[COB160]

Hi,
when I touch the screen of my Hp prime calculator in order to see calculus's history, the calculator displays horizontal lines as a interference... is it normal?

Another problem I have is that when I type this integral

https://www.dropbox.com/s/c14kw9gsmpltrb...4.GIF?dl=0

wich has simple result (displayed in the image I linked), it appears a hourglass in the place of the battery status and it happens 2 kind of things:
Either the calculator restarts displaying hp logo and a big (x^2+y^2=1) expression or the calculator does not respond any more. I am now waiting for the calculator to run out of power.

How can I fix these tho bugs? they happened since I bought the calculator.

sorry for my English

[Joe Horn]

(07-10-2017 01:01 PM)COB160 Wrote:  ... the calculator does not respond any more. I am now waiting for the calculator to run out of power.

No need to wait. Poke a paperclip into the reset hole in the middle of the back of the calculator.

[COB160]

(07-10-2017 06:02 PM)Joe Horn Wrote:  

(07-10-2017 01:01 PM)COB160 Wrote:  ... the calculator does not respond any more. I am now waiting for the calculator to run out of power.

No need to wait. Poke a paperclip into the reset hole in the middle of the back of the calculator.

Ok, it works! about the lines on the screen that seems an interference?