On some occasions, my X10 will not turn on. Turn the zoom ring and it won't go on, then off and on again usually fixes it. Anyone else had this issue? Almost seems like the internal switch has an issue...
One thing that helps to reduce this issue - if you remove the card from the camera, lock the card before inserting it into any device. After you're done downloading, eject it the right way, then unlock the card and put it back in the camera. I haven't had to reformat once since adopting this habit.
Unfortunately, I ran into Catch 22 with the Apple Camera Connection SD card reader for iPad; it wouldn't read the card if it was locked! PITA....
I started having the same problem shortly after getting my X10. I did some research and found that a lot of times reformatting your card when you first reinstall it in the camera will solve the problem. I tried it and I haven't had the problem since. Just an idea...