1

Please help. AVAST blocks this when I open firefox or Crome. But why is this malware not detected when you scan? Why cant AVAST remove this?

2

tohotweb is a BHO, a browser parasite, that can only be removed in Safe Mode.

Wait for a qualified malware remover here to see whether your have been infested by it,
and then when that is the case to help you with removal of this pest.

polonus

3
AVAST blocks this when I open firefox or Crome. But why is this malware not detected when you scan?
It depends what the avast message say? could you tell us or post a screenshot

for help, follow instructions >> https://forum.avast.com/index.php?topic=194892.0

4

If you post the Malwarebytes and FRST logs, I will be happy to assist you in making sure this is removed.