Backup freeze at validating image for client : hostname

Hi,

we upgraded netbackup from 7.1 to 7.5.0.5 and we have some problems. One of them is related to the validation of the images in the backup process. IT works for some backup and not for others. We ae using disk pools for backup and the hardware behind are Datadomain unit.  HEre is an example

 Info bpbrm(pid=1512) validating image for client : hostaname.

Ususally this process takes 30 sec but now it can run for 5 hours and nothing is moving so I need to cancel the job.

Also, i don't know if it's related but since the upgrade, when i open a disk pool, i can't refresh the volume. The error is  : invalid comman parameter. RDSM has encountered an issue with STS where the server was not found: getDiskVolumeInfoList.

Thhanks for your help