Many people seem to be experiencing this annoyance. Here's a similar complaint about what appears to be the same issue: http://support.mozilla.com/en-US/questions/813865 This is a deal-breaker for me if it is not fixed. SOON. The last comment in thread from the above link is: "Here, use this Tab add-on; it's the only way to do it in Firefox 4." Unacceptable. If a browser can't be set to reliably open to a user's choice of homepage, then it's a pretty cartoonish failure of a browser.