After rebooting my Windows 7 x64 Build Agent ( I did not disable it on my GO server ), my W2008 GO Enterprise Server statused it as "missing" and as Subversion had several check-ins, I had several pipelines in schedule mode waiting for this one Agent that had resources assigned. After I discovered that the only Agent was in "missing" status, I cancelled all the pending job queues.
Even though both my Agent and Server services were running, since my only Agent was in "missing" status, I restarted both agent and server services and verified both services were running again.
I also verified the "missing" Agent had the same IP as what's in my server cruise-config.xml.
UUID for the Agent on my server cruise-config.xml matched what's in the Agent guid.txt.
What action fixed it? I don't know for sure but waiting five minutes had something to do with it.
I originally was writing this post to ask for help as my GO Agent was still in "missing" status. However, just before I was about to post, I rechecked my W2008 server and the Windows 7 Go Agent was back in healthy idle status. Seems it can take a few minutes for Agent and Server to re-sync up after an Agent OS reboot or a client service bounce.
Next time before I reboot an Agent box, I'll play nice with my Server and I'll set the Agent status to disabled. I wonder though if the Agent and Server would have re-synced up on their own and if cancelling the queued up pipelines was necessary...