I have a virtual machine running Windows 2008 R2, that also has SQL 2008R2 installed.
I rebooted the server.
I was able to RDP into the Windows server like normal, once the reboot was finished.
However, it took SQL nearly ten minutes to allow connections. When I opened the SQL Management Console, I used Windows Authentication, like normal, but it wouldn't allow me in. I even tried other accounts that had the passwords saved in cache, and they were not allowed in. I waited for a while, tried again, and then I was allowed in. I was not typing in the wrong password, as that information is stored in cache.