Spark locks up when user sends to one user

I have a very strange issue. We have 20 plus users using Spark for many years. I have one user that every time he tries to IM me specifically, his Spark locks up completely. It only happens when he send a message to me. i tried deleting his user and creating a new one. We tried uninstalling and reinstalling Spark on his computer. No matter what we try it acts the exact same way.

what does the mean lock up??

if it happened when he typed letters and sent it to you? can you attach the picture when the spark lock up?

i wish i could help you, because i’m also the beginner of openfire and spark

This can be related to a corrupted history xml file. Though you said yo uhave deleted his user, but you then created it with the same username? Then he must be using the same profile. Go to transcripts folder in his profile and rename a history file with your username. He will have fresh history file with you and maybe locking up issue will go away.

C:\Users\username\AppData\Roaming\Spark\user\username@servername\transcripts\