Datasafe recovery disk error

Making system recovery disks and after asking for the 2nd disk I got:

There is not enough space on your hard drive You can either free up space on your local hard drive or use a directly attached storage device(Key or externalHDD) to perform this action.

The whole window locked up and the only way to kill it was to use the task manager to killl the application. Not very impressive software!!!!

Anybody have any idea what is going on? BTW i have 870GB of free space on my hard drive. Sorry if this is posted in the wrong place.