Backup Error 507 is generally a result of an I/O problem with the target device.
Some possible causes of this error are:
target device is full.
a loss of connection on a network disk (especially with wireless networks).
a firewall blocking access to a networked backup device
hardware problems with the a disk, disk controller or network
a "bad spot" on a CD/DVD disk (possibly cured with a reformat).
out of date driver software for a CD/DVD writer
The error will also occur if attempting to save a backup file greater than 4gb on a disk formatted with the FAT32 file system. You must use the NTFS disk format if files are larger than 4gb. Alternately, all of our backup programs allow you to save the backup file in smaller 'chunks' to avoid the 4gb limit of FAT32.