hello canehan10, if it is reappearing that indicates that there is another part of this malware active on your system outside of firefox.

run a full scan of your system with different tools like the free version of malwarebytes, adwcleaner and microsoft safety scanner to see if they can catch the malware...

See also http://malwaretips.com/blogs/dp1815-virus-removal/

Thanks all. It appears to have been solved by AdwCleaner, after the restart. I have to say to the team behind AdwCleaner that for a non-expert, knowing what to have removed or not from the registry is very daunting. Finally I opted for nothing to be removed, then ran CCleaner's registry cleaner.

I realise AdwCleaner is a free program, and thank you very much for that, but if you could find a way to give a bit of advice on cleaning the registry it would be very helpful.

Perhaps as a first step, would it be possible to highlight the items that definitely have to be removed because of what the scan has found ?

please let adwcleaner remove all the instances it has found - it isn't a registry cleaner but scans for adware and browser hijackers. every entry it finds will be related to adware and should be deleted...

Phillip, thank you very much, I'll run it again and do that. Perhaps a note on the screen to that effect for the timid, like me, would be helpful ...

Philippe, I ran it as suggested.

However, when I tried to install Hosts Anti=PUP/Adware from the Tools tab on AdwCleaner, it was blocked by AVG. It reported

"";"Virus identified Worm/Autoit.AZCH, c:\Users\PT\AppData\Local\Temp\HOSTS_Anti-Adware.exe";"Infected"

and deleted it. Over to you ...

i suspect this is a false positive, but you don't need to install this component. it's enough if you just run a one-time scan with adwcleaner.

Thanks/