Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller (for more info, see this alternate TDSSKiller download page)
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Currently running Windows 10 Pro w/Malwarebytes - just completed a Malwarebytes scan with no problems noted. I find it interesting that www.apusx.com appears to be a Google page of some sort.

Have you tried changing your homepage in about:preferences? There is another forum user with a similar issue.

This could be from a bad add-on.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

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

Site comes back clean on VirusTotal: https://www.virustotal.com/#/url/634ea2c367910638811ca14cabbc6b2085aca90bbf17ee94e6a5eb1519c213f2/detection

No joy after disabling extentions and plugins. However, I've found it works correctly if Firefox is started via 'Run as Administrator'.

Also see this question.

1) Created new profile with cnn.com as the home page. Still loads apusx.com on start.

2) www.apusx.com was the setting for the following registry keys:

HKEY/LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/Explorer/StartPage

HKEY_USERS/.DEFAULT/Software/Microsoft/InternetExplorer/Main/Start Page

I set both these keys to www.cnn.com - still no joy. No further instances of 'apusx' could be found in the registry.

Finally - success with RegRun Reanimator.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.