Microsoft SQL Server could not save the security changes

I have this error running MS Sync Centre on a Win 7 machine,
My replication model works OK on XP
The instance at the Subscriber is SQLEXPRESS 2008 r2
all 3 logins Distributor, Subscriber and Publisher are Windows Authentication
I am using my login which has Full permission and I have tried running Sync Centre as administrator all return the same error

I have successfully created and run a subscription on the same machine with an instance of SQL Server standard and that works OK as well

I have spent some time searching but not found anything which solves the problem

any help anyone?

Thanks in advance and happy New year

jnc