Trojan - Remove Failed

Hello everyone, first posting on this forum but I've been a Norton user for years now.  Windows 7, all going OK, but Nortin picked up Trojan.Smoaler today.  It says the risk is high, but 'Remove  Failed'.  however, on the Actions Required' screen it says "all detected security risks have been resolved".  

 

On 'Scan Details' it says "Total security risks found = 3)  (2 were cookies).  "Total security risks fixed = 3".  But click "Details" and it says that there is one unresolved security risk = Virus unresolved.  

 

So I'm baffled, is it fixed or not?  

 

And how did it get through?  I have Norton 360, regular updates, regular scans.  Don't open dodgy emails (can't say the same for Mr. Fluffpot, however!).  But surely this shouldn't have got through Norton, should it?

 

Please advise.

 

Big thanks for your help.  Fluffpot