dclk signal in cyclone 5 is sent again and again.

i am using altera cyclone 5 device, which is programmed through epcs16. initially for 2-3 days my card works well, but after that cyclone 5 is sending dclk signal again and again. i changed epcs16 and also resoldering cyclone 5, but the problem is not solved. i am facing this problem in 2-3 cards. kindly suggest me the appropriate solution for this.