Huh. I have an alu iMac with a 500GB HDD. There is about 200GB free. Every time I run the Bootcamp Assistant, choose a Windows partition (doesn't matter what size), it sits with the progress bar spinning for ages before it gives me the error "Disk could not be partitioned as some files cannot be moved. Please reformat the disk and try again". What gives? There is no way I can back the disk up, reformat, reinstall and re-update everything. No other apps are running when I run the Bootcamp Assistant. Any ideas?