two problems with logins that may be (and i think are) related

Hi All,

I have researched this odd problem for the last month or so and tried so many things I would not be able to list them here.

The problems in brief are:

1. Outlook 2013 (and 2010 I think) occasionally asks for password to extra accounts (multiple businesses - some people have accounts for multiple domains) without accepting any credentials (despite them being correct). restarting outlook solves this problem.
2. to try to solve the above problems I setup "Add-MailboxPermission -Identity jd -User jimd -AccessRights FullAccess -Automapping $false" which in theory then requires no extra authentication for adding the extra account. the problem is that we now cannot send emails from these extra accounts (which are added into outlook as separate accounts)

Now, the problem with #1 possibly appeared shorlty after I finally got the OAB working (mostly - I think ... always via activesync). As I said in the first line, I have tried an awful lot of things. a few things that I have found that do not work are:

1. nltest /sc_query:domain.local returns "I_NetLogonControl failed: Status = 1355 0x54b ERROR_NO_SUCH_DOMAIN" from the exchange server, but authentication appears to be OK, and I am receiving successfully machine authentication from this server, so I am hesitant to try to reset this machine account, and am unsure what this will do to the