Have got this issue on both a Vista and XP machine and sounds very much like the following problem
Basically even though I know for a fact that there are updates to receive live update reports "no updates found" then continues to tell me my definitions are out of date. If I download the latest definitions (Manually) it all works. But this is something I dont want to be doing.
I have used the removal tool and re-installed with reboots as per the above posts. No effect.
Have also used the one click with a chap who logged on remotely to the Vista Laptop.
He stopped all un-needed services and left symantec running after a reboot NIS2009 successfully picked up an update. Now that the other services are running again its all ticking over nicely... I dont understand how this could of worked and the same thing has not worked on the XP machine. Any one got any ideas?