Need Help removing a trojan

ok so 3 days ago i download a video codec, now when i tried to install it, both Windows Defender and AVG anti virus said that it contained a trojan and a pop up enabler. So i deleted it and did a complete scan of my system with both Defender and AVG. They both found something and reoved it.
But the thing is whenever i reboot my computer, Defender always gives a warning that trojan Renoz.dz is present. (sometimes AVG also gives a warning) Now i have rebooted my computer abt 10 times and selected remove when the warning pops up. But it still comes up when ever i restart the computer.

And after the warning when i select delete, i do a complete system scan but nothing is detected. And the process repeats itself when i restart

 

boot into safe mode then run a scan.

else google for a remover for that specific Trojan / instructions on removing

 

download Malwarebytes' Anti-Malware

its the best i've seen

 

Also try shredding the infected file.

I suggest Simple File Shredder or AxCrypt Shredder.

 

Make sure system restore is disabled because some viruses piggyback on it and restore themselves using system restore.

Don't forget to turn it back on when the virus gone.

 

I second royk50.

 

I also agree on malwarebytes. It is a phenomenal program.

 

try Avast antivirus, it's free, and it's pretty powerful. Hopefully it doesn't resort to a format/reinstall =(

 

in order to remove it properly, it's good to know
- where is it (system volume information, temporary internet files, temp, windows\system32, ..., - where?)
- when does it come back - if it does (after restart? what if you restart when the internet is unplugged?)
- what is the filename and the threat name as detected by avg?
- what will scanning in the safe mode do? sometimes trojans are held by running processes and therefore cannot be deleted in normal mode
- try using ccleaner to see what's on the startup list... the trojan or its part will most probably sit there

and after you get rid of it, you'll know that you should never ever launch anything you don't know or are not absolutely sure about.

 

The best way to remove persistent pests from the OS is to boot into safe-mode and scan the system via antivirus from there.

I also recommend Spybot.
Download it, update it, re-boot into safe-mode, scan the system with your antivirus first, then with Spybot.
Clean out anything that is found, and you should be good.

 

Some of those trojans are very difficult to remove. They embed themselves to start automatically when your system starts. They are also difficult to find because they are named like they are part of Windows OS and will even go into the Registry. My friend caught one of these viruses and had to reinstall his system.

 

To be sure that Malwarebytes'Antimalware (or any other program you used) has succesfully removed the trojan, follow the instructions on one of these fora; BleepingComputer or MajorGeeks.
Follow every step recommended, only then you can be sure you're clean.