Understandin backup error messages

I posted this yesterday, but can't fint it in the forum now, so am re-posting!

Does anyone know what the following report means?
"Failed to open backup G:\BackupsC\C_Drive_2013-12-13_PC01_19_full_b5_s1_v1.tib. Make sure the backup location is accessible and contains all versions of the backup. This backup may also be corrupted."

There is plenty of room on the backup disc which is not corrupted.
All I am trying to do is get it to do a full back up of my C drive. yet the stupid program keeps looking for another backup of my C drive done months ago on a different portable disc. It does not finish, sends me meaningless e-mails, ending with
41 True Image 18/02/2014 18:05:07 The specified file does not exist.
42 True Image 18/02/2014 18:05:07 The system cannot find the file specified
43 True Image 18/02/2014 18:05:09 Operation has completed with errors.
Why on earth should the program look for old back ups when it is doing a new complete one?
Where does one start to fix this?
Any help would be gratefully appreciated.