Let me explain a little bit more.
There are two domains: Domain1 ( NT4 ) and Domain2 ( Win2k ). Between the two domains there is a trust, so users in Domain2 can access resources in Domain1. This trust also is necessary to migrate the accounts.
The migration tool used is FastLane Migrator ( this can be compared with ADMT, but more advanced features are available ).
The migration we do is import the SamAccountName ( used to logon in W'98/NT ) and the SIDHistory of the NT4 account into the existing Win2k account. In this way resources are available through the Win2k account on the NT4 domain using the SID of the NT4 account, so re-ACLing is not necessary.
When the user is migrated, the Kix script doesn't recognize the user belonging to the group it seems... And therefore doesn't map the drives.
To me it looks Kix is looking at the Win2k SID of the account, and not looking at the SIDHistory.
I guess there must be a way Kix can refer to the SIDHistory???