I was informed by my ISP that there have been malicious attacks coming from my family's machines (4 computers, 2 mobile devices in total), a product of the Zeus trojan. So I ran avast full scan on my computer and was shocked to see it pop up with 58 infected files. However, before the full scan was completed my computer shut down for some reason (overheating?). After I rebooted the computer, which strangely opened with a windows update screen, I ran another full scan and avast detected no viruses. I find this very suspicious. I also tried Norton Power Eraser, and it turned up with nothing.
What should I do?