Seems like it has reached end of life cyle.. thats why the problem with liveupdate.
when new viruses come, new definitions should take care, the virus is quarantine. it would scan when new defs arrive.
the virus might still be in your machine and might have disabled symantec, thats the reason why scan is not happening.
I would suggest you to run a full scan using symantec online scan.
upgrade your version to newever sav 10.x or sep 11,
as far as quarentine is concerned ,yes you can delete those folders without any issues.
if you manually want to delete those folders you need to assign permissions and delete the folder.
F:\Documents and Settings\All Users\Application Data\Symantec\Symantec Endpoint Protection\Quarantine
https://www-secure.symantec.com/connect/forums/sav-corporate-9-end-life
https://www-secure.symantec.com/connect/forums/error-0x20000058 check shp suggestion ,run full scan only after that upgrade your antivirus.