Did you post this from the laptop? Do you have any kind of blocking program? Have you had any other problem?

Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences<Enter> in the address bar

Select Advanced > General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

Yes, I am posting from the laptop.

I had no problem accessing a number of web sites in safe mode, but the sites that I wrote about are still not accessible.

I don't have any blocking program, other than the Norton firewall. The sites in question are not accessible even with the firewall disabled.

Only one other problem, which is that Shockwave Flash doesn't load on boot, and takes a long time to load on the laptop when a web site calls for it. It keeps popping up a message asking if I want to continue. Once it finally loads, everything seems to work properly, except for the problem with the web sites that will not load. Shockwave apparently loads on boot on the desktop, because I've never seen the message that it needs an OK to continue.

See also:

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

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

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

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware