Pentax Optio 555 Digital Camera.

Question

Pentax Optio 555 Digital Camera. Once I have taken a couple of photos in a row, the camera continually flashes red & green. Like it is continually thinking. I cannot then even get the camera to shut down eithout removing the battery or just leaving it until it times itself out.If i remove the battery, I still have to turn it on & then off again to get the lense to retract. Can you help to solve this problem. It does it no matter what the charge in the battery is like. Full or half used.