I've had no issues with data backup on my external hard drive since I got my iMac over a year ago. There was always plenty of space to make daily backups and last time I looked my data was backed up from about January. Yesterday my backup failed for the first time. The volume saved to disk is 223GB and the computer says there's not enough free memory for further backups (only about 9.5GB left). Going into Time Machine I can see I've lost all my backups before yesterday lunchtime. I've been trying to identify what I might have done to cause this and the only thing I can come up with is data capture overload during the importing of video from a camcorder into iMovie and/or Final Cut Express. Is it possible there are stray files left over from my video editing that are clogging up my system? I've checked out my Final Cut Express Documents files but nothing here seems to add up to the huge amount of data which seems to be causing this problem. If this isn't it then I don't know where all this extra data has come from... How can I find out where this extra data is which is preventing Time Machine from backing up? Is it possible there is some problem with Time Machine configuration? Right now the configuration window reads this: Do not back up: Time Machine Backups (this is greyed out) 223.4 GB Total included: 248.9 GB How can I solve this problem and get Time Machine working normally again? Thanks in advance.