Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

What is your home page?

My homepage is Mozilla. Here's a copy of the update screen.. Thanks.

No this isn't part of Firefox and it looks suspicious to me.

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender: Home Page:
  http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

You may have the Express Files Updater application installed as look for the efupdater.exe

http://www.processchecker.com/file/EFupdater.exe.html

I've tried completing a System Restore, but it won't complete because of a program that's running, even when I've turned everything off, so I'm assuming this EFU file is causing the problem.

I've just tracked the file down in my Program Files (x86) folder, deleted it, and emptied the Recycle Bin... but if my IT guru is right, it'll still be hidden in the file it came in, and will come back again.

Watch this space!