nixCraft

Hi All,
I have my squid proxy server running (2.6 Stable) on fedora core 6 with Dansguardian as the webcontent filter. it runs very well i used it for almost 10 days i had no issues. just couple of days back when i checked my internet usage from the ISP for 2 days there was a download of 18 GBS. it didnt happen from any of the computer in the network. intrestingly when i unplugged my proxyserver from the network and used a simple squid for proxying, for an hour or so there was only 8mb of usage. i have a doubt is this happening cause of Squid? or Dansguardian? or the Machine it self? is there anything wrong that d machine is downloading something automatically? some help on this is really appreciated.
Thanks in advance!