What you’re seeing first is almost certainly the JPEG preview embedded inside the RAW file. Cameras save this preview so software can show an image quickly.

A moment later, Picasa switches from that embedded JPEG to its own RAW rendering using the codec/default conversion settings. RAW data is not a finished image, so it must be interpreted and processed to display correctly. Different software uses different defaults, and those defaults often look flatter or less saturated than the camera-made JPEG.

So nothing is wrong with your files — you’re comparing the camera’s processed JPEG preview to Picasa’s default RAW conversion.

If Picasa offers only limited RAW controls, there may not be much you can do inside it to match the camera look. To keep that look, you’d typically need software with better RAW adjustment options, or shoot RAW+JPEG and use the JPEGs for browsing while keeping RAWs for editing.