You might find this helpful. Try reading all of it before doing anything, and see if you recognize your situation. One thing to remember is that any time you install software, you should go slowly and read the options carefully (even if you are doing an express install), because almost all software now tries to automatically install toolbars like this without your knowledge. When they do this, there is always an option to either check or uncheck (like “Yes, I want to install the Link All My Words To eBay Toolbar”, or what have you).
Based on that link, I’m guessing that it’s something installed on your computer, but not technically malware. If you are worried about a malware problem, I would recommend downloading Malwarebytes to scan your computer. The great irony is that, since the download is being hosted by CNet, it will very probably also try to install a toolbar that you don’t want. You have to be really careful about this stuff these days.