Printer got stuck

My friend is using a Hp640C colour printer,it was working well, but nowadays when he gives a print the printer cartridge gets stuck while printing and its power led and paper feed led starts blinking alternatively.He is not able to continue the print,then he should clean the sides of the cartridge and switch off the printer and then on to continue.It happens very often,eventhough the printer is kept in a clean atmosphere.(it is kept in a chilled room,will it cause the problem).I am confused about it please help me.
Thanks in advance.