Hi,
Issue has occurred due to low disk space.
Message in the log is very clear "2014-08-14 02:54:09.627 THREAD 32 SEVERE: Your hard disk space is less than <512>MB. Symantec Endpoint Protection Manager requires more disk space to complete certain tasks. Please delete some files to free up some space. Symantec recommends that you have a minimum of 1GB of free disk space."
To make free space follow this article
http://www.symantec.com/docs/TECH96214
Apart form it, you can try the following workarounds as well.
1) Move the recent backup to another location. Default location would be C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\data\backup - This is a temporary workaround.
2) Delete the older version packages if present any and they are of no use.
SEPM --> Admin --> Install package --> Right click on old package and select delete.
3) Make sure database maintenance is taking place, check the database settings.