I have a Delphi app using the GW Admin API that occasionally gets a error when changing a DN with a MoveWithinTree call. The error is "Access violation at address 0045762B in module 'NetSync.exe'. Read of address 00000000"

I'm sure this is simply the result of a bad param and is not my main problem. My problem is that this application is handling a batch of updates and once it gets this error for one account, it fails with the same error for all successive accounts. My code is similar to this:

try
vSystem:=CreateOleObject('NovellGroupWareAdmin');
vSystem.Connect(GWDomainPath);
ConnectedtoDomain:= true;
Except
on E: Exception do
ConnectedtoDomain:= false;
end;

Loop for each user in the batch
try
vDomain:=vSystem.ConnectedDomain;
vUser:= vDomain.Users.ItemByDN(CurrentDN);
vUser.MoveWithinTree(New_DN);
Except
on E: Exception do
FlagError
end;

Do I need to renew my system connection for any error?

Thanks,