Images or animations do not load
From MozillaZine Knowledge Base
This article is about problems loading images (PNG, JPG, or GIF) or animations. It does not cover problems with video or plugins such as Flash. Those can be found in Video or audio does not play.
- In your Options/Preferences settings,
- Hold down the <Shift> key and click the Reload button to force a fresh reload of the page .
- If you are using anything to block webpage content (e.g., Adblock or Adblock Plus, or a hosts file), disable it.
- If you use ZoneAlarm Pro or eTrust Firewall, see the Security software section below.
- If you have enabled network.http.pipelining (a "tweak" designed to improve page loading time), disable it in about:config by typing "pipelining" in the filter and right-clicking all entries and choosing Reset. (If you set this preference by editing the "user.js" file, remove this edit.) Some websites do not support pipelining, which may result in images not being sent.
- Clear the cache. In Firefox: "Tools -> Options -> "Advanced -> Network / Cache (or Offline Storage) -> Clear Now" (or use "Tools -> Clear Private Data", if "Cache" is selected in your Privacy / Private Data settings). In Mozilla Suite/SeaMonkey: "Edit -> Preferences -> Advanced -> Cache -> Clear Cache".
- Remove cookies. In Firefox: "Tools -> Options -> Privacy / Cookies -> Show Cookies" (or use "Tools -> Clear Private Data", if "Cookies" is selected in your Privacy / Private Data settings). In Mozilla Suite/SeaMonkey: "Tools -> Cookie Manager -> Manage Stored Cookies".
If none of these suggestions help, try the rest of the solutions in this article.
Images do not load
Make sure that you are allowing all images to load and that images from specific sites are not being blocked:
- In Firefox, look under "Tools -> Options -> Content" and
- Make sure that "Load images automatically" is checked.
- Open [Exceptions] and remove any sites being blocked.
- Use about:config to make sure that the preference permissions.default.image is set to "1", the default value (right-click and select "Reset" if any other value is shown). 
- In Mozilla Suite/SeaMonkey, look under "Edit -> Preferences -> Privacy & Security -> Images" and
- Make sure that "Accept all images" is selected
- Open [Manage Image Permissions] and remove any site listed with the status, "site cannot load images".
Other reasons that images may not load:
- If images are blocked on site, click on the location bar's favicon for "More Information" and check the Media tab there for "Block images from ...". (If it is check-marked, you probably did not open the Exceptions button above).
- Even if you can see the site and some images, third party images may still be blocked from other sites by Extensions such as "Adblock Plus" or with a hosts file.
- The site hosting the images may be down or experiencing difficulties, try loading the site from another computer or browser to see if this is the case.
- A router or security software is blocking what appears to be an excessively large number of connections (interpreting it as a "SYN flood"). This can be caused by changing network settings in Firefox, or by inappropriate settings in the router or security software.
- Images from a site can be blocked from a context menu (right-clicking, in Windows). A site could be blocked accidentally by right-clicking on an image.
- Some image references contain backslashes (e.g. something.com\blah.jpg), which cause the images to be loaded in Internet Explorer but not other browsers. If you see the image's URL contains a backslash, contact the webmaster about the issue. The Slashy extension will let you work around this problem.
- Some sites will block the request if no referring URL is sent. Use about:config to make sure that the preference network.http.sendRefererHeader is set to "2" (default) and reset, if necessary. Also make sure that all proxies, firewalls, and other security software allow the referrer to be sent.
- As a security precaution, references to images on your local computer from a remote web site are disabled. If you encounter this restriction and you understand the security implications, you can disable this security measure.
- Problematic extensions can cause images not to load. If you have one of these extensions, you can disable it in Firefox via "Tools -> Add-ons -> Extensions":
- Among other issues, the Skype extension for Firefox (installed with Skype) can prevent images from loading and causes the error, The image cannot be displayed because it contains errors.  
- The "RealPlayer Browser Record Plugin" extension (included as an option when installing RealPlayer) can cause images on a web page to no longer display if you reload the page 
Many of the solutions under Error loading some websites and Websites randomly don't load will also fix image loading problems.
Images load but look wrong
- If the colors appear wrong, try the solutions in Website colors are wrong.
- If you are using any sort of web accelerator software, disable it and see if images load properly.
- If the image is very large, Firefox by default will resize it to fit inside the browser window. If you prefer to see the image full size you can either click on the image to resize it, or, in Firefox 1.5, you can go into "Tools -> Options -> Advanced -> General" and un-check "Resize large images to fit in the browser window". (Starting in Firefox 2.0, this option has been removed from the user interface .)
- If you are using the Image Zoom extension, go to "View -> Image Zoom -> 100% (Original Size)". Additional support for Image Zoom
Images load as text or gibberish
See Page displays as gibberish.
Images do not animate
Access about:config and find image.animation_mode, which determines how to animate multi-frame GIF images. Reset the preference to the default setting, if necessary. Possible value are:
- none: animated images will never play.
- once: animated images will play once.
- normal (default): animated images will play as normal.
- Some security software may block certain images by identifying them as "web bugs" or may stop .gif image animations. If you are using ZoneAlarm Pro or CA (eTrust) Personal Firewall, do the following to correct these problems:
- Open the Firewall Control Center.
- Select "Privacy" on the left tabs.
- Select "Custom" in the Cookie Control section.
- Uncheck the box for "Disable web bugs" in the "3rd Party Cookies" section.
- Select "Custom" in the Ad Blocking section.
- Uncheck the box for "Animation", as shown here.
Images still do not load correctly
If you have tried all of the solutions in this article and images or animations still don't load correctly: