I've been trying to clean out a HP desktop computer which is infested with malware. For some reason, my brother or a program uninstalled Avast Free Antivirus.
With the help of Adwcleaner, MalwareBytes Anti-Malware, avast!, ESET online scanner, Spybot — Search & Destroy, Emsisoft Emergency Kit, Bazooka Adware and Spyware Scanner, and HitmanPro, I've removed over twenty infected files and folders, malicious registry keys, tracking cookies, and malicious files. Most are PUPs and adware, but Avast found a Trojan which Microsoft Security Essentials detected when it was transferred to Avast's temp folder.
I also tried scanning with Zemana AntiMalware, which couldn't install, and TrendMicro Housecall, which stalled at 28%. The thing is, I tried scanning with ESET again yesterday, and it found four infected files. However, I couldn't remove them or even see what they were as the program stopped responding (tried twice). I then deleted ESET from my Downloads folder.
Also, I notice the computer is VERY slow. I know it has been slow ever since we bought it, but it's much worse now. I looked at this article, followed most of the instructions except dusting the inside of the computer.
One more thing — sometimes when I turn on the computer, I get a strange error message something like: "Windows can't open up this file". That applies to all files (including EXEs). A restart solves it. (I apologize for not taking a picture of the message!)
Would someone please help me make sure the computer is no longer infected? If you would like, I can attach the logs. (I'm not sure whether if I should be posting them here.)
Model: HP p6536f connected to a HP 2310m monitor
Operating system: Windows7 Home Premium (64-bit)
Processor: Intel Pentium
HD size: 1 terabyte
System memory: 7 GB