"...Used By Another Process" errors are all caused by other software on your computer or another computer on a network using a file you are trying to back up. These can almost always be ignored because they involve temporary files used by Windows which are either recreated each time Windows starts or whenever Windows is reinstalled.

The only thing to be careful of is if you are running other software while the backup runs, because the other software may have files open that you really want to include in the backup.

The backup software is designed to suppress these errors for files it knows are harmless, but it can be fooled about which files these are by how you have configured Windows. In general, if you have an excessive number of these errors it is safe to exclude the following folders from your backups:

c:\windows\system32\config
c:\winnt\system32\config
c:\documents and settings\(login name)\local settings\temp
c:\documents and settings\(login name)\local settings\temporary internet files
c:\documents and settings\(login name)\cookies