when you get the error
The application can not add more files because the vault’s disk is full.
check that your file names do not use reserved characters. take a look here for a list of such characters
http://en.wikipedia.org/wiki/Filename
do not hit the ok button on the error message, rather drag that error box a little bit and behind it you will see the progress box which shows file name and some other info. this is the file that is causing the error. if the file name uses reserved chars, rename the file and try again to put it in the vault.
