To avoid this autoupdates , just go to mt4-menu Extras->Options->Server
and check procy server, click on proxy button and type in something useless like 1,1,1,1 and ok.
Now mt4 cant connect to the internet for auto updates.
I had a similar problem but it was too late.
After i connected my broker changed the symbolname form XAGUSD to SILVER, and XAUUSD to GOLD,
that sucks , becuase now th backtest for that symbols dont work anymore.
(neverchange a running system ;-))