i need to know how to fix my peugeot 306 XSi immobiliser?

my immobiliser started playing up about 2 weeks ago on my peugeot 306 XSi 2.0,1996. i turn on the ignition and both lights on the immobiliser come on, which means i can't enter my 4 digit code. i disconnect the battery for a while and then it's ok for a bit. but just recently it is doing this nearly every day. is there a way around this? do i need to get a new immobiliser keypad?

this is very frustrating, i daren't go anywhere in my car. can you help!!!