Would the SQL Server instance go offline if it couldn't write to any of the Windows Event logs?
Found these two errors in the Windows Systems Event Log:
The system failed to flush data to the transaction log. Corruption may occur.
initerrlog: Could not open error log file 'E:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Log\ERRORLOG'. Operating system error = 5#Access is denied.#.
From what I can gather, these issues are related to our SQL Server instance going offline completely.
I've verified the security of the SQL Server Agent and Database Engine service accounts have the required access to the aforementioned log path. There is nothing in the SQL Server Error logs or the Windows Logs that state things were changed by someone or that that they automagically lost their access some how.
Let me know if you need more info and thank you in advance for any pointers you can provide.