I have 8i and 9i running on the same oms machine. OMS and the agent pickup both versions.

What platform are you having the problem on? Win/Unix/Linux? If on Win, make sure the service "startup type" is "Automatic" and it probably wouldn't hurt to check your logs.

If on Unix/Linux, check your startups (/etc/rc) for "oemctrl start oms" and "agentctl start".