Back so soon...
C:\WINDOWS\Application Data\Mozilla\Firefox\Profiles\pdkpbfjy.default\Cache\_CACHE_002_
C:\WINDOWS\Application Data\Mozilla\Firefox\Profiles\pdkpbfjy.default\Cache
These locations are your FF Browser cache. Where IE would store in Temporary Internet Files, FF has Cahce folders.
Open FireFox. Go to
Tools > Options - in the Privacy Tab, click to Clear Cache.
I would reboot and then let Symantec do a virus scan.
Again, you have the online scans at your disposal.
Let us know what you find.