K, I see. Your browser if deffo hijacked though. I take it you are using IE7? If so then goto a page you want to set as your homepage, then click on the Home icon at the top of the browser, then add or change homepage, then the top option. Let me know if this fixes it. You could always do a complete browser reset via tools, internet options, advanced tab and then click reset.
Just seen this:did you install anything like this; LinkedIn: LinkedIn Tools: Browser Toolbar
Ive been reading about this toolbar and it poses a security threat. It is recommended to uninstall this asap if you have this.