Issue with inbound queue processing in PI with user XIIFUSER

We are facing some issue with Inbound Queue processing in PI 7.0.There are queues starting with XBTO* which are going to RETRY status and then getting processed either very slow or after manual processing.Below is our analysis:

•          The error is coming, not only for any particular receiver service, so there should not be any issue at Receiver end.

•         The user is same for all the these failure cases which is XIIFUSER.

•         Messages are getting processed after automatic restart or after manual processing.

•         Other queues with XIAFUSER are getting processed normally with error.

•         The issue is started after  ECC upgrade activity.

•         As per our analysis passwords are different for XIIFUSER in ECC & PI system.

Your suggestion are much appreciated on the issue.

Thanks in advance for your help.