OptiPlex 7010 Hangs Every 3.5 Days

So, this is admittedly a weird one... Every 3.5 days, just like clockwork, my OptiPlex 7010 will hang/crash and create a packet storm on the network. The packet storm is so severe, it will take down the entire network. The only way to recover is to physically power cycle the computer. Since this is a refurbished unit, I don't want to spend a lot of time/effort/money on troubleshooting. But, I thought I'd throw this issue out there to see if anyone else has had the issue. Thanks.