I tried this charger from my friend and when i use it the charging works but the touch response of my N8 was terribly slow i cant use my phone.
is this okay? should i avoid using those kinds of charger..and someone know why this is happening?
using my old charger and it works fine same with the touch
Welcome to the Nokia forum.
It can't hurt the phone if you charge it with a non-Nokia charger, though I would personally
always recommend to use a charger that is compatible with your phone and recommended by Nokia to make sure the battery will be charged to its full potential. The compatible Nokia charger for your N8 is the Nokia High Efficiency Charger AC-15.
Is this okay? should I avoid using those kinds of charger and someone know why this is happening?
You don't say whether this is high output charger of say 2000mAH but obviusly electromagnetic field produced by it is too high for screen grounding upon your N8.
Symbian specialist until 31/01/2013 with interests in Maemo & MeeGo but an aversion to Windows!