Hi,

Please try scanning your computer using your Anti-Virus software to ensure that there is no running adware, viruses or any other malicious software on your computer.

Thank you!

Hello Adriel, thanks for your answer. I finished doing that a while ago, the antivirus spotted several infected files on the computer and deleted them... but the browser still has the same problem. It will not assume any other start page, no matter what I do. I truly don't understand what could be wrong here.

Does this appear when you launch a new window (Ctrl+n) in place of your home page, or only when you use the Firefox shortcut on your desktop or taskbar?

Some malware will modify your browser shortcuts. To check for that:

right-click the Firefox shortcut > Properties > Shortcut tab

For 64-bit Windows, the "Target" should be no more and no less than the following:

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

If anything follows that, make sure to remove it.

It would be the same idea for IE (but I'm not familiar with IE on Windows 8.1)

By the way, the Refresh feature creates an Old Firefox Data folder on your desktop that has your old settings folder. I suggest retaining that for a week or two in case you discover something critical is missing from Firefox after the refresh.

Thanks, jscher2000! That was it. The shortcut to Firefox still had the link to mystartsearch. I was able to remove it thanks to your advice. (Also, the Old Firefox Data folder you mentioned... It had traces of mystartsearch too. Amazing how deep this thing goes.)

Adriel, thanks again for your advice. I thought that by deleting the affected registry entries manually the problem might had been solved, but the antivirus scan really was necessary.

Thank you so much to both of you. The relief feels good. :) Learned some neat tricks too.

Hi, there are detailed steps to manually remove Mystartsearch in this post. I think it will be helpful!