When I click on an 'url' in an email (& I've tried a different program) 2 browsers open at once. 1 with the url, & 1 with my home page. How to fix?

I thought it was Incredimail doing this, tried uninstalling and re-install. Then it not only opened 2 browsers, it gave me errors and opened the email in the browser! Couldn't reply to anything. so I switched to Mozilla Thunderbird. Had to re-build my address book. Very irritating. Now the same thing is happening. Didn't do it the first 2 days, now it is.