I just finished with a visit to one of my clients. We were investigating why several users could not use a specific invoicing site. The first thing I did was connect my MBP to their wireless network and try the site in question. Bing! Everything worked great. That eliminated the possibility of there being a systemic network/firewall problem preventing the site from functioning properly. Next I went to the user who submitted the problem. When I sat down at his desk and tried to get to the same site that just worked fine on my Mac I was deluged with popups, redirects and more ads than I could sift through. Holy crap! I wondered how this guy gets anything done on this machine. He had TrendMicro installed as his security suite so I decided to run a quick scan of his C drive. Within 5 minutes with only 10% of the drive scanned, TrendMicro found 18 threats. I immediately went to the next room and shut down my Mac. This network was completely compromised.