Not enough disk space for backup

Hi:

 

I've got a little problem with the backup utility on 360, ver 2.5.0.5.  When I tell the backup utility what to back up to the online secure storage, (270.0 megs), Backup fails with a message that says, "Backup failed because you do not have enough free space for your backups.   My C:\ drive has 161 gigs free, an external drive I have plugged in via USB has 191 gb free, and there are no other drives.  The backup site has 1.9 gb free. 

 

Any ideas?

 

Thanks in advance.

 

Hope everybody has a merry Christmas.