I just downloaded an update from MS for Mac. Afterwards, I noticed that when I click on a new tab my top sites are gone and the'Bing' site is there

Delete a possible user.js file in the profile folder.

SEE: https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save#w_user-js-file-overriding-preferences

Also use the searchreset tool.

• https://addons.mozilla.org/en-us/firefox/addon/searchreset/

I jsut realized the actual page that comes up on the new tab is a url called 'search conduit', which i believe is a virus.

Yes Conduit can be removed using the method i posted in my last post.

QUOTE:

Delete a possible user.js file in the profile folder.

SEE: https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save#w_user-js-file-overriding-preferences

Also use the searchreset tool.

https://addons.mozilla.org/en-us/firefox/addon/searchreset/

You may also wish to remove it from the control panel, or using malwarebytes, with a reset of firefox.

SEE ALL BELOW:

• http://www.malwarebytes.org/products/
• Disable or remove Add-ons
• Refresh Firefox - reset add-ons and settings

Also check for suspicious extensions in "Tools > Add-ons > Extensions" that might be causing this

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