This was quirky. I put the camera on raw only for the first time today and my computer wouldn't even recognise there was a card in the reader. Thought it might just be an iMac thing but, although it recognised there was a card there, my husband's PC wouldn't recognise the photos. It had worked perfectly when I was shooting in raw + jpeg. So, I put the camera back on raw + jpeg, shot one photo, inserted the card and hey presto it recognised it and all my raw only shots were there also.

Would be interested to hear from any other Olympus users how to get around this. Otherwise I guess I can just shoot one shot raw + jpeg then change the camera to raw only.