Antivirus weird behavior after enabling vt-x

I wanted to enable vt-x because it was enabled on BIOS but it wasn't in Windows 7. I did a research and found that I could use bcdedit.exe /set nx {current} always on to enable it.

I dit it from cmd and restarted the pc, now it is enabled but then I saw something weird:

1. AVAST ANTIVIRUS CANNOT START HIS SERVICE working but is fixed by removing some files but I can't install it.

2. I can't install any antivirus and the error says A Device Attached and Not functioning (any device are enabled) so any are enabled (except the spame inteet and spame webcam).

My computer specs:

• DELL INSPIRON 5558 THE FIRST MODEL

• INTEL CORE I7 5500U WITH graphics 5500

• Nvidia geforce 920m

• 3.1TB samsung hhd

• Wireless and bluetooth by intel

• Realtek audio (waves maxxaudio)

How can I solve the antivirus problem?