Error: Invalid Windows logon credentials, please contact your administrator.
The issue is within the windows credential provider. How MyPC works, is that when it passes the credentials to the PC, it ALWAYS validates against the domain to confirm the credentials are correct. If this can't happen or there is a disconnect, the message you see is what you'd get. The reason why you don't see this when you log in with the Windows account directly is because the account is cached. (Think like taking a work laptop home and logging into a domain account. This is cached and not validating the account on the domain). This is usually a domain trust issue.
Best/quickest option is to remove the PC from the domain, and then re-add it. This should resolve the trust issue, OR at least give you a better idea/error about the problem.