possible causes:
a security patch is in-progress
an in-place upgrade is taking place
Troubleshooting approach:
double check that either the applied patch or upgrade is in-progress and not finished. And, check the logs for failures.
Temporary workaround:
starting up the database engine with trace flag -T902
important disclaimer: this is a workaround to allow other accounts can authenticate against MASTER database system and outage is ended. it’s very important that you open a case with Microsoft to figure out the root cause of the problem you are facing and fix it permanently.
sql server warrior 