If you have the problem with both browsers, the problem is on the computer. Check your firewall and virus protection.

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

I had a similar problem but found it was router related, as when I tried another router I could access the National Lottery site again. The problem was that for a DNS server I was using 'Level3' dns addresses of 4.2.2.3 and 4.2.2.5 - When I changed to any other dns server like OpenDNS (208.67.222.222 / 208.67.220.220) or Google (8.8.4.4/8.8.8.8) then then I could access the lottery. I remember I HAD been looking at the router settings and must have changed something, though God knows what, as it was ONLY Lottery access that was affected. I've got a Billion 7800N main router, so just went to 192.168.1.254 in the browser, and reset as much as seemed in any way sensible, and it finally worked. Still don't know which setting it was though. Prior to this I HAD tried a router reset but that didn't fix it. Maybe worth trying a different DNS if nothing else works for you anyway!

Just re-read my post and wondered if Level3 has some kind of moral clause which prevents access to gambling sites? Just an idea!

FredMcD said

If you have the problem with both browsers, the problem is on the computer. Check your firewall and virus protection.

I only have the Lottery page problem with Firefox, IE works fine, bit irritating that.

Scaramouche said

I remember I HAD been looking at the router settings and must have changed something . . . . . Prior to this I HAD tried a router reset but that didn't fix it.

With any program; If you just want to look around, that's fine. But when you are done, ALWAYS press the Cancel button, Just in case. Also, when you make changes that you might forget, write them down ! ! !

The Reset, in some cases, dose the same job as a re-boot. Check your instruction guide.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.