suddenly change: idmap uid + gid

[Hilberg]

Hi

The server suddenly changed the uid + gid. this happened to times, 
yesterday and the week after.
The samba is a AD member where we have many users (>20 000) and we use 
autorid in that way
[global]
	security = ads
	workgroup = CUSTOMER
	realm = CUSTOMER.COM
         winbind use default domain = yes
         winbind enum users = yes
         winbind enum group = yes
    	idmap config * : backend = autorid
	idmap config * : range = 1000000-8999999999

At the moment I have two questions:
Why this happened and is there a way to stop the disaster?
Is there a quick way to repair the disaster? I infects the profile 
directory used with acl.

thank you