Most likely to be spell-checker if it's just random words, colour comes up saying it's wrong, it's not, color apparently is how it's spelled. It's the US spell-check thingy.
Your original post suggested that the phenomenon is related purely to this website (because you mentioned the name of a dormant AB member) but your further posts suggest that your computer has acquired Text Enhance, which is a well-known piece of adware (a.k.a malware).
PS: Many of my answers are based purely upon 'theory' or upon Google searches. The one above is based upon experience. I've had exactly the same problem myself in the past!