Many site issues can be caused by corrupt cookies or cache.

Clear the Cache
Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

and

Remove Cookies
Firefox/Tools > Options > Privacy.
Under History, select Firefox will Use Custom Settings.
There is a button on the right side called Show Cookies.

If there is still a problem, Start Firefox in Safe Mode
While you are in safe mode; Firefox Options > Advanced > General.
Look for and turn off Use Hardware Acceleration.
Poke around safe web sites and see if there is still a problem. Then restart.

I found that after Firefox v29, a LOT of my settings and
add-ons were changed / reset. Try this;
Start Firefox in Safe Mode
While you are in safe mode;
Firefox Options > Advanced > General.
Look for and turn off Use Hardware Acceleration.
Then check ALL of your settings. Browser and add-ons. Then restart.

Thanks, before I posted the comment and restored my computer I had already cleared the cookies and browsing history and it still is not helping. Some pages will load and let me access them but others just hang up - this seems to something with all browsers that I've tried....Foxfire, Chrome, and Explorer....I've contacted 1 of the vendors but they know nothing....my computer did it's internet and network checks and don't find anything wrong....I'm frustrated because I know enough to troubleshoot basic issues but not anything beyond and leave "standard" setting so I don't want to start messing around with things..... How do I tell if it is a browser issue or the sites I'm contacting or my computer?

Call your internet provider and have them check your service.

It could be the work of one of your add-ons, or even add / mal-ware. Look thru your add-ons list and make sure you know what each one is there for. Also, check the programs that are on your computer Windows > Start > Control Panel > Uninstall Programs. Go thru the list and use a web search to check any that you don't know what they are.

Troubleshoot Firefox Issues Caused By Malware