rouge web browser that seemed fixed with update now back,this is a firefox problem

Could you be a little more specific about what the warning says?

If you are getting a pop-up urging you to call a toll-free number, perhaps with a voice in the background, that's a tech support scam and usually indicates you stumbled into a bad website rather than your own system being infected. (As long as you don't call them and give them remote access to your system!)

If you press the Esc key several times in a row quickly and the dialog keeps coming back, look for a checkbox toward the bottom left of the dialog which says you do not want the page to open any more popups or alerts. Check that box and click the OK button on the lower right. Then you should be able to close that tab normally.

If we assume you're getting to these pages through malware ads on popular sites, you might consider using an ad blocking extension. This one is well-regarded: https://addons.mozilla.org/firefox/addon/ublock-origin/

Does that help?

And "just in case," this support article suggests numerous free cleaning tools (completely free, or free trial) which can identify and remove a wide variety of annoying programs and add-ons: Troubleshoot Firefox issues caused by malware.

If you get a pop-up message asking to update Firefox or plugins or scanning for malware then such a message is likely a scam and you should NEVER respond to such an alert to avoid getting infected with malware.

• only update Firefox via "Help -> About" or by downloading and installing Firefox from the Mozilla server and never via a pop-up or link on a web page.
• plugins should only be updated via the plugin itself or by visiting the home page of the plugin.

See also:

• https://support.mozilla.org/en-US/kb/i-found-fake-firefox-update