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

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

Type about:preferences<Enter> in the address bar.

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

I finally solved my problem of some web sites not scrolling or showing a back button on any of their links, using Firefox 38.0.1 on my Mac!

I downloaded a previous version (37.0.2) and installed it, replacing v 38.

All the sites worked/scroll bars returned/back arrows returned!

There must have some undiscovered anomaly in v 38 for Mac users. I did not try it on a PC. I hope Mozilla finds it and fixes the new update.

Well, not a solution, but what works, works.

Safe Surfing.

You might experience this bug that happens when you are running Firefox in Private Browsing mode and you open links in a new window.

• bug 1166066 - Firefox 38 regression: link in private window with target="_blank" opens window with no tabs/toolbars/menus (bug1166066)

Possible workarounds: (1) use Options/Preferences > General: "Open new windows in a new tab instead" (2) Shift+click links to open in a new window with the standard features or use the right-click context menu.

The developers are working on a fix for this problem. Meanwhile, here is a third workaround:

(A) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(B) In the search box above the list, type or paste feat and pause while the list is filtered

(C) For every preference that starts with dom.disable_window_open_feature. if it is not "true", double-click it to switch it to true.

You may find that you prefer this anyway, since sites can no longer strip these features out of pop-up windows. On the other hand, if a site displays a tiny window, you may need to enlarge it now that it will have toolbars.