This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

When viewing email on Outlook in Firefox, there now appears a rectangular black box over part of every email.

  • 3 replies
  • 1 has this problem
  • 1 view
  • Last reply by FredMcD

reiter2000
reiter2000
more options

When viewing email on Outlook in Firefox, there now appears a rectangular black box over part of every email. This does not occur when viewing Outlook emails on Chrome or Edge. I thought it might be because of my adblocker (Ublock Origin) so I turned it off, but the black rectangle still covers part of my messages (and I have Ublock on Chrome, too, with no problem viewing Outlook).

The rectangle covers only a portion of the messages. When I scroll the message, the black rectangle remains stationary and the message scrolls behind it, thus revealing the portion previously covered by the black rectangle (a different portion of the message becomes covered).

I tried to take a screenshot to show the black rectangle covering part of the message. Amazingly, even though the black rectangle is there when I take the screenshot, the screenshot itself does not display the black rectangle....instead the message appears in the screenshot without being partially covered by the black rectangle.

When viewing email on Outlook in Firefox, there now appears a rectangular black box over part of every email. This does not occur when viewing Outlook emails on Chrome or Edge. I thought it might be because of my adblocker (Ublock Origin) so I turned it off, but the black rectangle still covers part of my messages (and I have Ublock on Chrome, too, with no problem viewing Outlook). The rectangle covers only a portion of the messages. When I scroll the message, the black rectangle remains stationary and the message scrolls behind it, thus revealing the portion previously covered by the black rectangle (a different portion of the message becomes covered). I tried to take a screenshot to show the black rectangle covering part of the message. Amazingly, even though the black rectangle is there when I take the screenshot, the screenshot itself does not display the black rectangle....instead the message appears in the screenshot without being partially covered by the black rectangle.

Chosen solution

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

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

If there is still a problem,

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

While you are in Troubleshoot(Safe) mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

Read this answer in context 👍 0

All Replies (3)

FredMcD
FredMcD
more options

Chosen Solution

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

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

If there is still a problem,

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

While you are in Troubleshoot(Safe) mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

reiter2000
reiter2000 Question owner
more options

FredMcD:

I had already tried clearing the cache before posting my question. I followed your suggestion to disable graphics hardware acceleration but that did not resolve the problem. Then I followed your suggestion to delete the cookies (I only deleted the cookies related to the Outlook website).....that worked to eliminate the problem !!!

Thank you very much for your help, Fred.

FredMcD
FredMcD
more options

Glad to help. Safe Surfing.