Pvp freezes realm

In my realm, players may engage in combat. But most of the time a player is hit by anything player-related, except for explosions and pets, the realm will freeze and roll back to a previous backup. Most times the backup was ~20 minutes before the freeze. Now when you leave, it won't let you join back for about 20 more minutes. This issue has frustrated many of my members and wastes so much time.