My guess its a problems with the track journal.
Fist messages is only info <2>, but right after down to the 1/1000 of second we see the error message.
I think fscp_add_tj_entry is must be read as "File System Copy add Track Journal"
Try rename the existing the track journal and run a new full classic backup
23:59:53.919 [5052.6036] <2> fwrite_and_log: fail to write <fix size entry block> for track journal, backup id:<NULL>, file:<desktop.ini>, err_num:<2>, to write:<1>, wrote:<0>
23:59:53.919 [5052.6036] <4> dos_backup::fscp_add_tj_entry(): ct_cat_add_entry() failed, error:<14>.
23:59:53.919 [5052.6036] <16> tar_backup_tfi::fscp_finishfile_state: ERR - fscp_add_tj_entry() failed, error (14)
Update: Do you got TIR enabled as well ?
True Image Restore with move detection should not be enabled in NetBackup policies where Accelerator has already been enabled.
http://www.symantec.com/docs/TECH216391
The Technote is valid for 7.5 as well and a EEB exist for 7.5.0.7