Hi,Hmm I bought some extreme 30mbps cards from sandisk and I encounter the card error problem too! Sometimes I try to turn off the camera but it doesn't turn off until i takeout and reinsert the memory card. Gets annoying at times
Have you upgraded to the latest firmware?
After I had upgraded mine, there problem has not occured yet.
I have tried shooting time-lapse in RAW with 2secs interval for 50 photos... and then follow by another set of 50 photos with 2 secs interval again... No problem thus far.
Just to share my experience here.