Firefox 44 Not Loading Pages After Modem/Router Change

[CrypticQuery]

I recently received an updated Gateway from my cable company, replacing my old, separate modem and router.  After a successful installation (and significantly increased internet speeds, might I add; I went from a C- to an A on Speedtest!) I discovered that Firefox no longer connects to the internet.  Its pages load in an infinite loop, regardless of the site accessed.  Both Chrome and Internet Explorer load pages perfectly fine, however.  

I've already tried uninstalling Firefox and reinstalling it, but to no avail.  I've ensured that Firefox is an accepted program in Windows Firewall, and that it also has no proxy configuration selected in its network settings as well.

I should also add that it periodically crashes upon startup too.

[Arashikage]

Uninstall Firefox and make sure all of the files are gone.  When Firefox uninstalls there are still some folders and files left over.  To completely eradicate it you need to go into appdata or something.  There will be Firefox folders, you should get results if you use the search function.  

[CrypticQuery]

Thanks for the quick reply. 

I discovered the Appdata leftovers on my first uninstall and made the necessary changes for the second one onward.  It doesn't seem to help though - rarely, Firefox will load pages during a session when recently re-installed, but if that instance is closed out and reopened it goes into its endless loop again.  

[Clearwater]

I had a slightly similiar problem with an older version of Firefox a few months back, where it'd refuse to load up YouTube or Dubtrack without even trying, claiming it was a failed DNS resolving issue. It'd load up fine in Internet Explorer and Google Chrome though.

I don't know if these'll work, but I tried it on mine and it solved it:

Go into the command prompt and type in the following commands:

ipconfig /flushdns

netsh winsock reset

netsh winhttp reset proxy

netsh winhttp reset tracing

netsh winsock reset catalog

netsh int ipv4 reset catalog

netsh int ipv6 reset catalog

Once that's all done, give your computer a quick restart and give Firefox another try.

[CrypticQuery]

Thanks for the assistance, Clearwater, but it seems as if my problem may be simpler than that.  Firefox loads pages fine in safe mode with all of its addons disabled.  I'm in the process of testing each one individually now to see which causes pages to stop loading. 

EDIT: Well, that didn't work.  Firefox loads all pages perfectly fine while in safe mode, but not in the normal browser.  None of the installed plugins seem to be causing this.  I have no extensions installed and no personas active either.  

Edited January 27, 2016 by OneUnder

[CrypticQuery]

I solved my problem, and now don't have to relegate myself to using another browser.

It turned out that Avast Antivirus' Mozilla extension was potentially causing an issue.  I updated Avast, restarted my computer, and presto.

I appreciate the suggestions though!

[CrypticQuery]

It seems as if I was preemptive in my celebration.  Firefox has stopped loading sites, yet again.  It loads things perfectly fine while it's running in safe mode.  Disabling extensions does nothing, and refreshing Firefox doesn't mitigate the issue either.

EDIT: Intermittent problems are the worst problems.  It seems to be working perfectly fine now...