You should be using the Hikvision NVRs, not the iVMS4200 software for recording. I currently have a Milestone system using Hikvision encoders & Hikvision IP cameras. Both us (dealer) and the customer hate the Milestone - too prone to issues and video is mission-critical for this end-user (jail).
We are in the process of replacing the Milestone servers with Hikvision NVRs and will be using Hikvision Decoders to display live video on several video walls. The iVMS software should only be used as an interface to the Hikvision hardware - not as an integral piece of the system.
I have other installations using Hikvision NVRs, Encoders, & Decoders withe iVMS software in two gaming (casino) environments with almost no problems whatsoever.
BTW, I am factory trained & certified in both Milestone & Hikvision.