That's interesting. By which I mean: Depending on what version you were upgrading from, there might have been some service change steps post-install, but we've had tens of thousands of agent upgrades and thankfully this isn't an epidemic. It's possible if someone else was accessing/modifying the services area at the same time you might see this, there seems to be some weirdness in how Windows handles the locking around install/removal of services.
Now that you're in this state, you have two options:
- (Harder) Manually register the service with something like sc.exe from the resource kit (there might be other tools) - set it to match a system that is properly running the agent, if you need details I can help.
- (Easier) Use one of the agent installers and install over the top of the existing agent to put the service back
I used the second option (pushing the install over top of the existing one) and that seemed to work. Thanks.