As per my comments in your other thread:
"Soooo, looking at both your threads, it's possible that the issues are related. Lack of disk space will prevent the SEPM from updating its definitions. There are a few "Disk Space" related articles on the KB (a selection of which are below):
http://www.symantec.com/docs/TECH102927
http://www.symantec.com/docs/TECH196326
By the way, from the version number you provided, not only are you running a very old version of the SEPM, but it's also one that was very quickly replaced by a patched version: RU6a (11.0.6005.562). I'd recommend moving away from this version.
Finally, I noticed from your other thread that you provided a LUA screenshot. Is this installed on the same box as the SEPM? If so, this is not recommended:
http://www.symantec.com/docs/TECH93409"
Not only is the LUA not recommended for installation ont he same box as the SEPM, it can take up a lot of disk space. If it is on the same box, remove it