It seems that after my recent post moaning about the poor design of Windows Backup it has decided to get it's own back and now refuses to run with an unhelpful (and ungrammatical) error message! When tried to run my Backup (complete system image and selected User Data folders) it failed. The additional information pop-up box stated the following (in semi-English): "Windows Backup skipped backing up system image because one of the critical volumes is not having enough free space. Free up some space by deleting unnecessary files and try again. Error code: 0x81000033" Note that the Windows Backup pane has the following information clearly displayed at the same time: "Location: Backup_1 (G:) 71.52 GB free of 232.88 GB Backup size 10.98 GB" So Windows Backup thinks it has 71GB space free ... and it tells me there isn't enough space. That's helpful. It doesn't even tell me which "critical volume" needs more space. Or how much. Or why. It fails after it creates the folder <ComputerName> (ie. the UserData part of the backup) on drive G: This contains about 10.5GB of newly saved data so it has nearly(?) completed the backup of the User Data part. So this isn't a problem of the drive being inaccessible or unwritable. From previous backups I know that the User Data part of the Backup (<ComputerName>) will be about 11GB. And the System part of the Backup ("WindowsImageBackup") will be about 20GB. So why does it think it doesn't have enough space when there is 71.5GB free? All volumes on the PC have spare capacity, even those which are not being backed-up, or are not involved in the backup. C: - 11GB free (and 18.5 GB used) - C:/D:/E: are partitions of the main hard drive (RAID) D: - 33GB free (temporarily empty) E: - 318GB free (about 11GB of data in folders selected for backup, other archives managed seperately) (F: is optical media) G: - 85GB free initially (150GB used) - backup destination - this is a physcally different hard drive H: - 10GB free (not relevant to the Backup used for online archival) - this is another physcally different hard drive Backup is set up to write data from C: and E: to G: I have checked drive G: for errors and chkdsk reports that it is all OK. There are no other error messages. The system even log has identical text to the message I get from Windows Backup, so it provides no useful information. So what is Backup trying to do? And why doesn't it produce any useful information?