thanks a lot for your answer, and yes, this system ain't vanilla. I was assuming at first that there was some sort of policy destroying the tables, but nobody on our zone was aware of this policy implementation, and therefore I wouldn't rely on that assumption. Finally, yesterday when everybody came back to work after the holidays, we were informed that new security rules had been recently implemented and deployed, and these were the culprits... So, with this said... The issue got resolved.