Scanned system disappear from the database of opmanager.

Hi,

I've scanned lot of remote systems associated to my organization using Opmanager but unfortunately I have faced two problems:
1) During scanning the screen turns to blank.
2) Scanned systems replaced with each other. For example, I have scanned a remote system individually, say system A, the result is successful. After that, I tried to scanned another system, say system B, the result is successful too. But the problem is when I have checked the systems on that subnet inwhich they lies, system B is present but system A has been disappeared.
Next time, if I tries to scan again system A, the result is successful but it will replaced by system B (Means system B is now disappeared from the list of scanned systems)

Can somebody help me in this regard? I'll be grateful.

Regards,