I had a friends laptop on my network recently and found that he was infected. We did some scans to try and fix him up and then he left. But ever since his laptop was introduced to the network a good majority of my PCs, at least four, now will have explorer.exe hangs where I have to manually close explorer and then re-start it. I have noticed that the activity light on my Cable Modem as well as my router and switches seem to be hammering hard. The hard-lined computers all seem to be sending data constantly based on the indicator light on the NIC. Accessing network shares has been an issue, too. Currently I have removed all computers from the network save for the one I am on right now. I have run Malwarebtes, MS Security essentials, and combofix and really haven't found much of note and that hasn't really stopped the issue. So, I am just wondering if anyone can help me ascertain whether or not I am really infected. I greatly appreciate the help. BTW, all PCs are running windows 7. Thanks.