Constantly keep getting error 404, server not found

Question

Very frequently I keep getting the error message 404, server not found. This problem mainly comes up after I have been on the computer for a while, and I leave the web site that I'm viewing on for some time. I then return to the computer some time later, and when I try to refresh the page to update the info on the page (example: a weather site or yahoo stock market info) I keep getting, 404 server not found. When I try the option: try again, it does nothing to solve the constant problem. The only way I can get back to the web site and see updated info is to start firefox in safe mode. And, that does solve the problem. But why does this problem keep constantly occurring. And, why do I have to constantly have to restart firefox in safe mode to get going again. It would seem firefox should recognize this issue and solve it. I'm using what I believe to be the latest version, 15. Can someone shed some light on this issue? I did not have this problem with my older computer and an old version of firefox, version 3.6. But, since getting a new computer and using a new version of firefox, version 15, this problem constantly appears. Can some one help? Thank you.

Answer 1

Which security software (firewall, anti-virus) do you have?
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
Do a malware check with some malware scanning programs on the Windows computer.<br />
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.
*Malwarebytes' Anti-Malware:<br>http://www.malwarebytes.org/mbam.php
*SuperAntispyware:<br>http://www.superantispyware.com/
*Microsoft Safety Scanner:<br>http://www.microsoft.com/security/scanner/en-us/default.aspx
*Windows Defender: Home Page:<br>http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
*Spybot Search & Destroy:<br>http://www.safer-networking.org/en/index.html
*Kasperky Free Security Scan:<br>http://www.kaspersky.com/security-scan
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