System call Failed

NEtbackup 7.5.0.6 and Windows server 2008 R2 platform

We are getting some peculiar error message in full backup of a server in Image level backups using VM-Ware method.

Error message is System call failed.

And after running 250 GB of total 300GB its getting error but incremental backups for the server is running fine and File-Level (MS-Windows)

policy backups are running fine.