...that they called and told me that I had a zombie PC. I run updates, antivirus software and am very careful about where I go on the web, and what I download. Despite all my precautions, though, my PC got infected via an infected CD from my office (autorun is now turned off, btw).
I got a call from Comcast saying that they'd noticed some odd traffic. The tech guy said it looked like my PC had been infected although it didn't seem to be actively sending/receiving any unusual data. After a quick re-scan with my antivirus software, it was gone, and all was right with the world (well, my tiny corner of it, anyway).
I was used to Comcast sucking hardcore before this happened. Now my attitude is a little better toward them -- the Comcast tech guy knew his stuff, and was very helpful.