Is it possible that my computer has been infected and sometimes "attacks" my router and turns it off and if so would replacing the hard-drive with a new one solve this issue?
I doubt it.
Bad connections and drop outs can be down to many things too many people using the same wireless channel is the likely cause for students living in close proximity.
Poor wiring to extensions / bad filters / old routers
faults on the line external to your dwelling.
Out of date drivers / poor NIC cards / wireless cards etc.