Taken from Cyberscrub FAQ
When wiping the unused disk space on a drive or scrambling the deleted files and folders properties, CyberScrub creates a series of temporary files (.WIP files) in the root folder and fills them until there is no free space left on drive. Then it removes them from disk, thus freeing up the disk space. Each temporary file has up to 1 GB in size (if your drive has 3 GB of free space, CyberScrub will create three temporary files, it will fill them and then remove them from disk).
Sometimes Windows will warn you that you are running out of disk space on the drive where CyberScrub is wiping the disk free space. You should ignore this error, because CyberScrub will free up the disk space after it finishes wiping.
So it sounds as if this is a normal event and can be ignored.