Operating a small ISP, rest assured there is never a dull moment, and sometimes never a shortage of angry clients, especially when they have no internet.
Walking in to my office Monday morning. I was bombarded with several phone calls from clients saying they had no Internet access.
After about 12 calls and a client bringing in their laptop, I figured out the issue was with an automatic update from McAfee, after further reasearch I found several articles including this one from scmagazineuk.com where it talks about the issue.