Why did you do a reset?

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

I reset Firefox because my Google searches were contaminated with unwanted results - gambling sites etc. I did a full system scan with Norton - nothing found so therefore the reset, which cured the problem. I'll try restarting Firefox in safe mode and let you know.

Restarted in Safe Mode. Home pages came up OK (as always). One of the home pages (TV Guide) was plastered with ads (no uBlock). Closing one of the ads opened a tab with a warning "your Windows 10 system is seriously damaged" and with a link to repair it (so much for Safe Mode!). I closed the tab immediately and ran SFC /scannow. All is well with my Windows 10.

Tried accessing one of the problem pages - still showing blank. Tried Google Maps - still not working.

Do you see any error messages in the Web Console?

• https://developer.mozilla.org/Tools/Web_Console

You may have to copy the cert8.db file form the profile folder in the "Old Firefox Data" folder on the desktop to the current profile folder.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

ajpage said

one of the ads opened a tab with a warning "your Windows 10 system is seriously damaged"

. Whenever you get a message / popup like that;

DO NOT USE ANY OF THE PROVIDED LINKS OR ANY PHONE NUMBERS ! !

Such messages are only Spam that could lead you to Fake Support. Not only can they damage or hack your system, they charge you to do so.

You can report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

cor-el, No warnings on the SFC /scannow. I tried your suggestion of copying "old" cert8.db to "new". It brought back the original problem of contaminated Google searches and did not solve the blank page problem. I have reversed the change. I have performed another Norton full system scan - two tracking cookies removed, no other problems. Neither problem occurs using Microsoft Edge so I've concluded that it's associated with Firefox. Any other ideas?

So, there is a certificate issue if copying cert8.db to a new profile recreates your issue.

You can check the certificate chain chain with this corrupted vert8.db file in place to see what is going on.

• click the "Site Identity icon" (Control Center 'i' icon) at the left end of the location/address bar
• click the arrow to expand the security message
• click "More Information" to open "Tools -> Page Info"
• click "View Certificate" to inspect the certificate chain and check the issuer of each certificate

You may still have certificate issues in the new profile, but they manifest in a different way.

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

cor-el Many thanks for your latest reply. Before trying it I have some more information that might help with the diagnosis... I did a Google search to find the talktalk site and entered the site. uBlock came up with a warning blocking access because of a problem with google lead services (image 1). I disabled uBlock temporarily and another warning came up with a problem with doubleclick.net (image 2). Temporarily disabling again produced the now familiar blank page. I've also noted that Google keeps asking me to review my privacy settings. (I have three email addresses registered with Google and the problem seems to occur whichever one I use to sign in. Thank you for your help so far and for being so patient with me.

Yes as FredMCD said,

FredMcD said

ajpage said

one of the ads opened a tab with a warning "your Windows 10 system is seriously damaged"

. Whenever you get a message / popup like that;

DO NOT USE ANY OF THE PROVIDED LINKS OR ANY PHONE NUMBERS ! !

Such messages are only Spam that could lead you to Fake Support. Not only can they damage or hack your system, they charge you to do so.

You can report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

Also, if a website tells you there is "an urgent Firefox update" don't click it as this is spam as well and can damage your system if ran. Updates to Firefox are only provided by Mozilla, nobody else.