When you try to open Mozilla Firefox you get the above error message. Most likely you have been infected with a virus or malware that corrupted the browsers profile. After running your scans, you can reset the profile.ini file and re-access your browser, although your profile, including bookmarks, etc, will be gone. (Note the tips to backup bookmarks and favorites…)
To do so, click on Start, (or click on Cortana in Win10), and enter %appdata%. Click on the option that has Mozilla in the line. Click to open Mozilla, then Firefox and look for the file profiles.ini. Rename the file to profiles.old. Close the window and open Firefox again.