Thanx N.Nick for your time,
1. No Overclock just standard.
2. Used Multiplay same way weekly with others in Simvn.
3. Only thing changed was the panel of Kingair to Glass cockpit, but took it out to check & fault reoccured.
It happened after the the security install with SOBD, managed to to get all back, and a a couple of days later during Multiplay it conged out.
I had the second CDR-W disappearing from Win Explorer and then showing up again when I run INCD.
The fs9/Net heavy load seems likely as it happens after the chat is used.
Unless I hear otherwise from you, I will change all partitions to NTFS within windows as I am running OK & is not really necessary to reformat just for that.