New tabs should open by default as a blank tab with no web page on it.
If something else happens and a web page opens that an extension or other software is causing that.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

cleared the fault, thanks a lot,

yahoo is taking over our browsers...im trying to find a way to kill it

You probably have the yahoo toolbar. IT IS THE DEVIL AND YOU SHOULD UNINSTALL IT ;)

Anyways...to alleviate this stresser for now...start firefox in safemode (close all browsers first): Start menu -->all programs---> mozilla firefox ---> mozilla firefox (safe mode)

When the dialogue box appears...check "disable all toolbars and add-ons"

Then click "Make change and start"

The previously mentioned add-ons and Adware software is useful, BUT you still have to make changes in the settings and it is ONLY useful for future add-on/toolbar downloads.

Until I can figure out how to UNINSTALL that damn toolbar completely, I hope you find this to be the MOST useful (based on putting 2 and 2 together from other replies) ;)

BTW you and go back and enable individual add-ons (as needed) by going to tools --->add-ons----> enable (for specific highlighted add-ons)

AND you can customize your toolbar by right clicking a toolbar icon and clicking "customize"

I hope this has been helpful :)

Yahoo is one of the most annoying businesses. I'd like to sue them. Go to Tools | add-ons. Uninstall Yahoo Toolbar, and Disable Freeze.com NetAssistant. That should prevent this criminal intrusion by a scum company. NEVER use Yahoo.

Yeah, it was Freeze.com. Thank you!

I had same problem. Before, each new tab opened a new Google search page. Suddenly it began opening new tabs in only Yahoo! search. I uninstalled the add-on for Yahoo! (no idea how I got it!), but still had the same problem. Then I disabled the "Freeze - Net Assistant" add-on, and it WORKED! (Thanks).

But, now each new tab opens in a BLANK new page, rather than my old Google Search page. Can't seem to get it to open as it used to, in Google Search. I set that up under earlier version (now using version 4), but can't seem to do it in this newest version. Love some help. Thx.