Media Full after one backup operation.

I am running BackupExec 2012 on Windows Server 2008 with a QuikStor 320GB drive.

I have backup exec set to do a full backup on Friday night followed by incremental backups for the remaining six days.

I am finding that after the first backup that the backup drive is full even though the data on our server is a fraction of 320GB.

Looking at the files on the backup drive I see the following under the VERITAS\B2D:

You can see that there are a number of 52GB files created on Friday night and the early hours of Saturday morning !

The sum of the used space on all the drives being backed up totals under 100GB.

Can anyone suggest what is going on ?

Best Regards