Which security software (firewall, anti-virus) do you have?

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

If malware is preventing to download the files to the computer then you need to do that on another computer and transfer the files to your computer via a USB stick or via other means.

Thanks for the response. I've run Glary Utilities, Advanced Systems Care 5 Pro, F- Secure in my Anti-Virus, firewall, etc. And I keep everything updated.

I did nothing but download and run the FireFox update from their site and the verification of compatible add-ons. Then I lost access through the undated FireFox and IE too. I have no problems with SAFE mode however. It hung up when it begain checking the FireFox add-ons. It locked up. I re booted and couldn't access the net through FireFox OR IE. But Thunderbird works OK.

I'll check out some of your suggestions further.

A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

After reading your comments, etc. since it appeared to be tied to the firefox add-ons in some way. While 'in safe mode' I deactivated ALL the add-ons. And temporarily dumped everying from my startup menu except about 4 or 5 items.

I re-booted a few times. And I got to the point where IE worked OK but Firefox still wouldn't connect. I re-loaded Firefox and re-booted again ... and this time Firefox came to life. Everything seems to be working again ... I created a new restore point. And am moving forward.

If it hadn't worked, I was going to follow your protocol on removing all the rules and permissions.

Thanks again for your comments and shaking up my thinking!