Are you getting anything in the logs?
are you changing the setting through command line or through EPO?
I´m just asking, because if the MAC command line is recovered, there is nothing changed through the McAfee Agent.
The second Option could be, happened in my LAB environmen, the System Needs a reboot. You can check this directly in EPO. Click Solidcore on the installed products, scroll down, there is an entry is a reboot is required or not.
nothing in logs.
Well, after some digging I found the mfe agent was refusing to communicate with epo. redeploying the agent didn't work either so rebuilt the endpoint and now it works.
To Troja, I didn't see an 'Installed Products' listing in the system menu - is that under another name or a sub menu? My software inventory didn't have an entry for a reboot option (using both 5.1 and 5.3.
tested with EPO 5.1.1....it depends on the Status of your System if "reboot is required" is shown or not. This is not a fixed entry. Take a look at the screenshot.
It would be interesting what really happend on your endpoint. I a production environment a complete reinstall of the System is not necessary when removing the product completely and reinstall it afterwards.