A possible cause is security software (firewall) 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 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.com/kb/Server+not+found
• https://support.mozilla.com/kb/Firewalls

To be more clear, you are having trouble connecting to mozilla.org or mozilla.com with Firefox ?

Firefox can't establish a connection to the server at search.imesh.com.

This is the error mx I keep getting. Thanks for trying to help!!!

• Can you connect to other sites ?
• Did you try the links James provided above ?
  • what happens if you type into the location bar http://mozilla.org/ and click on the green arrow ?
• Try clicking on the link I provide (it says post in blue) does that work ?
  or are you not able to open anything in Firefox?
  what about files saved on your local computer do they open ?

Possibly you have some sort of malware, or at least some searchbar that you are not expecting, see also this post suggesting:

Close Firefoz and open c:\program files\imesh applications folder

if you see any uninstall.exe program, run it;

then remove datamngr and media bar from firefox add-ons.

if still you see that lovely page (search.imesh.com), then remove data manager and media bar folders from imesh folder.