modem prob plz help

[cnu_raop]

hi ..my modem Nokia siemens networks c2110when i switch off my modem and switch it on later it has got 4 led lights power ,link,data,pc/usbwhen i switch on my modem the link,data,pc/usb lightskeep on blinking for very long time,at the point of blinking network shows unpluged.then after sometime link led light and pc/usb light become stable then i will be able to connect to internet.please tell me wats the problem..thank you