Is this inside the tab you are loading or could it be a pop-up ad in a separate window that is getting shut down part way through loading or just after it loads?? A pop-up window would add a new "layer" to the combined Firefox icon on the Windows 7 Taskbar, but if you have multiple windows open, that might be hard to spot.

Are there particular sites where you notice this, or is it happening on numerous or all sites?

In case one of your extensions is involved, could you test the problem page(s) in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

this does not happen every load so it is difficult to tell what is effective. I have Java toolkit but is deactivated. After requesting a new page there is a pause state, also obvious when photo not present, but when photograph is presented it is displayed. Believe that the connection is hacked and this is how photographs become available 2-3 times a night photographs of a local nature so two issues for me. 1. trace the hack. 2. Stop photographs displaying. would also like to capture photographs but this has evaded me so far. Would appreciate guidance on what mechanisms are being deployed.

Hi cire, when you view the Add-ons page, you will see multiple categories on the left. The one affected by Safe Mode is Extensions. Did you review those or only Plugins?

You can view your Firefox connection settings here:

"3-bar" menu button (or Tools menu) > Options > Advanced > Network mini-tab > "Settings" button

By default, Firefox has "Use system proxy settings" which should piggyback on your Windows/IE "LAN" settings. You also can try "No proxy" to see whether that changes anything.

Hacking investigation is somewhat beyond the scope of this forum, but you could start by keeping Firefox's Library dialog open to History (Ctrl+Shift+h) and looking to see whether unexpected pages are showing up at the time you see photos.

To supplement your regular security software, you can use the tools listed in our support article: Troubleshoot Firefox issues caused by malware. Those are free and take time to run. If they finish quickly and demand payment to clean what they find, you may have a very serious infection and should try the specialized cleanup forums listed in the article.