Well, if it's taking you to a web-page(like going to google.com, yahoo.com, etc, but for that Blekko thing), then follow these steps:
For Internet Explorer, click on the small gear icon in the top right, select "Internet options." Now a window should pop up and you'll see a white text box somewhere near the top of it, and above it will you'll see it say that this is the URL for your Home Page. (Which is what website your browser automatically loads whenever you start it.) Erase whatever is in the box and type "http://www.google.com/" but without the parenthesis.
If I'm telling you about the wrong thing entirely...Then I'll go on to the next thing that I think it could be...Which is an add-on.
So here we go:
For Internet Explorer, click on that wrench icon again and select "Manage add-ons." Now that you're here, you'll have to navigate through the list of toolbars, extensions, and other things that you may have. Well, whatever you've downloaded should say "Blekko" on it, at least I think it should...I've never really done this before so that's my best guess. But when you find what you're looking for, select it, and then at the bottom of the window on the right-hand side, you should see a button that says "Disable." Click it. If anything else pops up, well, I'd say just press Yes...Or agree to whatever it's asking you to do.
Hopefully this helps. And if you have anymore details to post after trying any of these just update your question, I'll be back to check up on this tomorrow to see if I can be of anymore help.