ok, the support of my datacenter give one task, to increase the disk space quota, because has beeb exceed... but in the increase of the quota, the plesk control panel give a message error, where are indicated the name of file with a large name!!!!!!! yes! are a attached file in one mail account. the name of the file have 263 caracteres. in the windows explorer the file cann't been renamed, moved or deleted. then i will go in the DOS prompt, go to the directory of attachments of this mail account, and rename it by DOS command. then delete it, and now the backup complete sucessufully again!!