"Are you registered" trashed prefs...

Sometimes in the mornings when we start Nuendo, Have to reselect ASIO card, and it asks if we want to Register Nuendo. We also have to replace a port Setup.xml.
We have 2 studios, different sound cards, but this problem is only with one machine.
Only since N 7.
Virus scanners avoiding anything Steinberg.
Becoming a daily occurance.

Think its unique to our machine not a Nuendo problem.

Fixed buy having a copy of working Prefs(app data) on standby, and replacing the broken Prefs.

Has anyone else had this problem??? Any hints on where to start looking???

Prefs are written on successful program quit. Either Nuendo is crashing and corrupting them or you have a something like a scheduled backup or permissions issue.

Thanks. Will get IT to have a look to see what automated trickery is going on overnight.