VOX

Are you using dedupe or not after you follow that article? Have you enabled the dedupe option in the profile and if the backups are working with the dedupe enabled profile?  

By default your data on the DLO would reside on C:\documents and Settings\userprofile\localsettings\application data\symantec\dlo\.lm (For windows XP) and for windows 7 it would be C:\users\userprofile\local\appdata\symantec\dlo\.lm Under this you w...

Since you have upgraded from DLO 7.0 to 7.5 the profile that the users are using shouldn't have the "Enable Dedupe" option checked. Check that and let the backup run as per schedule and see how it goes. It should backup the file on the dedupe storage...

Did you also try to keep the UAC settings at the lowest to see if that helps. Try to exclude the DLO from SEP central management policy so that SEP blocking/locking is ruled out.