Hi, delete all references to the website in question, as shown under the heading 'How do I remove a single website from my history?' in this article - Delete browsing, search and download history on Firefox, then try the site again.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

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

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Clearing the cookies and browsing history did not solve the problem.

When I go to Yahoo and click sign in, I get a page with a list of countries and international dialing codes with the sign in boxes at the very bottom. After signing in and selecting My Portfolios, I get that same page of overwritten text I posted earlier.

When I started FF in safe mode, the page displays properly.

You can check the log in the Web Console for error messages and the Network Monitor (Firefox/Tools > Web Developer) to see if content fails to load or is possibly blocked.

• https://developer.mozilla.org/Tools/Web_Console
• https://developer.mozilla.org/Tools/Network_Monitor

Use Ctrl+F5 or Ctrl+Shift+R to reload the page and bypass the cache to generate a fresh log.

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

Here's the web console info before and after the refresh.

When I refreshed the page this time, I got more info. Sorry, but I have no idea what any of that means.

It turns out the problem is caused by AdBlockPlus. The page displays correctly when ABP is disabled on the page or on Yahoo Finance in general.

Hi winchman, Thank you for reporting back what was causing the issue. If disabling AdBlockPlus for that page solves the issue, awesome. I will mark your post as the solution.