I have hopefully now resolved the problem, thanks for all the comments. One of the pins in the cf card slot appears to have been damaged, I don't know how this happens exactly since the card can only go in and out one way and I'm always very carefull removing it. According to my retailer (jessops) canon are reluctant to repair these, seeing it as a none warrenty issue ( Im only assuming they must therfore be blaming the user). Anyway, I had a extended retailers insurance policy, so mine is still getting repaired free of charge. Maybe a word of warning to anyone else approaching canon for this fault. Please feel free to put me right on this issue as I am only making assumptions about canons policy on hear say.