Try using the Search Reset extension.
https://addons.mozilla.org/en-US/firefox/addon/searchreset/

That did not do anything.

You may also want to reconsider your installed extensions.

• CouponXplorer 5.75.2.64122 (5zffxtbr@CouponXplorer_5z.com)
• ShopAtHome.com Toolbar 7.1.1.2 ([email protected])

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

In safe mode, I get a blank New Tab. So I've disabled the 2 toolbars, and running it in regular mode, now I get the blank New Tab. I tried to reset the home page to Bing.com by dragging it to the home page icon and selecting "set as default", but it's not working. Looks like I got rid of Ask.com, though! Can you help with that last part? And how would I uninstall those add-ons? Thanks.

You can use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

If you do not keep changes after a restart or otherwise have problems with preferences, see:

• http://kb.mozillazine.org/Preferences_not_saved